Get rid of ANTLR3

[copierrj]

We're currently using both ANTLR4 (cql2) and ANLR3 (feature-info and featurestore-sql mapping expression). We should phase out ANLR3 by upgrading to ANTLR4 or use a handwritten parser.

[tfr42]

in 3.6.2 the PR #1889 and #1890 have been integrated

[copierrj]

I've been working on porting the featureinfo format parser to ANTLR4 but unfortunately that's nowhere near finished yet.

The current ANTLR3 based lexer and parser both make heavy use of specific implementation details that changed in ANTLR4:

• In ANTLR3 the order of rules in the lexer definition determined precedence. Unfortunately ANTLR4 uses a longest-match-wins approach. Therefore the lexer needs to be rewritten using the new 'mode' concept introduced in ANTLR4.
• The way embedding Java code in the parser definition works has changed in ANTLR4, requiring significant rework of the parser definition. In ANTLR4 every rule creates a context object that contains the return value(s) of the rule.

Another hurdle: the documentation of the format and the unit test do not cover every supported feature.

WIP can be found here: https://github.com/IDgis/deegree3/tree/antlr4_featureinfo