Fix incomplete -Q in docs and usage messages (#8095)

The -Q option can either take an integer (number of points a contour has to have to be plotted) or a minimum length in a variety of units.  The code parsed that but apart from the usage message the synopsis and docs did not mention the length choice.  This PR updates the synopsis and docs.

doc/rst/source/contour.rst

@@ -26,7 +26,7 @@ Synopsis
 [ |-J|\ **z**\|\ **Z**\ *parameters* ]
 [ |-L|\ *pen* ]
 [ |-N| ]
-[ |-Q|\ [*n*][**+z**] ]
+[ |-Q|\ [*n*\|\ *length*\ [*unit*]][**+z**] ]
 [ |-S|\ [*p*\|\ *t*] ]
 [ |-T|\ [**h**\|\ **l**][**+a**][**+d**\ *gap*\ [/*length*]][**+l**\ [*labels*]] ]
 [ |SYN_OPT-U| ]
@@ -185,9 +185,9 @@ Optional Arguments
 
 .. _-Q:
 
-**-Q**\ [*n*][**+z**]
+**-Q**\ [*n*\|\ *length*\ [*unit*]][**+z**]
     Do not draw contours with less than *n* number of points [Draw all contours].
-    Alternatively, give instead a minimum contour length in distance units
+    Alternatively, give instead a minimum contour *length* in distance units
     (see `Units`_ for available units and how distances are computed),
     including **c** (Cartesian distances using user coordinates) or **C** for plot
     length units in current plot units after projecting the coordinates.

doc/rst/source/grdcontour.rst

@@ -21,7 +21,7 @@ Synopsis
 [ |-G|\ [**d**\|\ **f**\|\ **n**\|\ **l**\|\ **L**\|\ **x**\|\ **X**]\ *params* ]
 [ |-L|\ *low/high*\|\ **n**\|\ **N**\|\ **P**\|\ **p** ]
 [ |-N|\ [*cpt*] ]
-[ |-Q|\ [*n*][**+z**] ]
+[ |-Q|\ [*n*\|\ *length*\ [*unit*]][**+z**] ]
 [ |SYN_OPT-Rz| ]
 [ |-S|\ *smoothfactor* ]
 [ |-T|\ [**h**\|\ **l**][**+a**][**+d**\ *gap*\ [/*length*]][**+l**\ [*labels*]] ]
@@ -177,9 +177,9 @@ Optional Arguments
 
 .. _-Q:
 
-**-Q**\ [*n*][**+z**]
+**-Q**\ [*n*\|\ *length*\ [*unit*]][**+z**]
     Do not draw contours with less than *n* number of points [Draw all contours].
-    Alternatively, give instead a minimum contour length in distance units
+    Alternatively, give instead a minimum contour *length* in distance units
     (see `Units`_ for available units and how distances are computed),
     including **c** (Cartesian distances using user coordinates) or **C** for plot
     length units in current plot units after projecting the coordinates.

doc/rst/source/pscontour.rst

@@ -29,7 +29,7 @@ Synopsis
 [ |-N| ]
 [ |-O| ]
 [ |-P| ]
-[ |-Q|\ [*n*][**+z**] ]
+[ |-Q|\ [*n*\|\ *length*\ [*unit*]][**+z**] ]
 [ |-S|\ [**p**\|\ **t**] ]
 [ |-T|\ [**h**\|\ **l**][**+a**][**+d**\ *gap*\ [/*length*]][**+l**\ [*labels*]] ]
 [ |SYN_OPT-U| ]

src/grdcontour.c

@@ -172,7 +172,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
 	GMT_Usage (API, 0, "usage: %s %s %s [-A[n|[+]<int>|<list>][<labelinfo>]] [%s] [-C<contours>] "
-		"[-D<template>] [-F[l|r]] [%s] %s[-L<low>/<high>|n|N|P|p] [-N[<cpt>]] %s%s[-Q[<n>][+z]] [%s] "
+		"[-D<template>] [-F[l|r]] [%s] %s[-L<low>/<high>|n|N|P|p] [-N[<cpt>]] %s%s[-Q[<n>|<length>[unit]][+z]] [%s] "
 		"[-S<smooth>] [%s] [%s] [%s] [-W[a|c]<pen>[+c[l|f]]] [%s] [%s] [-Z[+o<shift>][+p][+s<fact>]] "
 		"[%s] %s[%s] [%s] [%s] [%s] [%s] [%s]\n", name, GMT_INGRID, GMT_J_OPT, GMT_B_OPT, GMT_CONTG, API->K_OPT, API->O_OPT,
 		API->P_OPT, GMT_Rgeoz_OPT, GMT_CONTT, GMT_U_OPT, GMT_V_OPT, GMT_X_OPT, GMT_Y_OPT, GMT_bo_OPT, API->c_OPT,
@@ -233,9 +233,9 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	GMT_Usage (API, -2, "Fill area between contour with the colors in a discrete CPT. If <cpt> is given the "
 		"we use that <cpt> for the fill, else -C<cpt> must be given and used instead [no fill].");
 	GMT_Option (API, "O,P");
-	GMT_Usage (API, 1, "\n-Q[<n>][+z]");
+	GMT_Usage (API, 1, "\n-Q[<n>|<length>[unit]][+z]");
 	GMT_Usage (API, -2, "Do not draw closed contours with less than <n> points [Draw all contours]. "
-		"Alternatively, give a minimum contour length and append a unit (%s, or c for Cartesian). "
+		"Alternatively, give a minimum contour <length> and append a unit (%s, or c for Cartesian). "
 		"Unit C means Cartesian distances after first projecting the input coordinates. "
 		"Optionally, append +z to skip tracing the zero-contour.", GMT_LEN_UNITS_DISPLAY);
 	GMT_Option (API, "R");

src/pscontour.c

@@ -389,7 +389,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	const char *name = gmt_show_name_and_purpose (API, THIS_MODULE_LIB, THIS_MODULE_CLASSIC_NAME, THIS_MODULE_PURPOSE);
 	if (level == GMT_MODULE_PURPOSE) return (GMT_NOERROR);
 	GMT_Usage (API, 0, "usage: %s <table> %s %s [-A[n|<contours>][<labelinfo>]] [%s] [-C<contours>] [-D<template>] "
-		"[-E<indextable>[+b]] [%s] [-I] %s[-L<pen>] [-N] %s%s[-Q[<n>][+z]] [-S[p|t]] [%s] [%s] [-W[a|c]<pen>[+c[l|f]]] "
+		"[-E<indextable>[+b]] [%s] [-I] %s[-L<pen>] [-N] %s%s[-Q[<n>|<length>[unit]][+z]] [-S[p|t]] [%s] [%s] [-W[a|c]<pen>[+c[l|f]]] "
 		"[%s] [%s] [%s] [%s] %s[%s] [%s] [%s] [%s] [%s] [%s] [%s] [%s] [%s] [%s] [%s] [%s]\n",
 	     name, GMT_J_OPT, GMT_Rgeoz_OPT, GMT_B_OPT, GMT_CONTG, API->K_OPT, API->O_OPT, API->P_OPT, GMT_CONTT, GMT_U_OPT,
 	     GMT_V_OPT, GMT_X_OPT, GMT_Y_OPT, GMT_b_OPT, API->c_OPT, GMT_d_OPT, GMT_e_OPT, GMT_f_OPT, GMT_h_OPT, GMT_i_OPT,
@@ -445,7 +445,7 @@ static int usage (struct GMTAPI_CTRL *API, int level) {
 	gmt_pen_syntax (API->GMT, 'L', NULL, "Draws the triangular mesh with the specified pen.", NULL, 0);
 	GMT_Usage (API, 1, "\n-N Do NOT clip contours/image at the border [Default clips].");
 	GMT_Option (API, "O,P");
-	GMT_Usage (API, 1, "\n-Q[<n>][+z]");
+	GMT_Usage (API, 1, "\n-Q[<n>|<length>[unit]][+z]");
 	GMT_Usage (API, -2, "Do not draw closed contours with less than <n> points [Draw all contours]. "
 		"Alternatively, give a minimum contour length and append a unit (%s, or c for Cartesian). "
 		"Unit C means Cartesian distances after first projecting the input coordinates. "