changed ToDo to use github markdown with task lists

Author: dsisnero

Diff for: ToDo

@@ -0,0 +1,128 @@
+
+- [x] copy to buffer if non-contiguous.gc
+- [x] contract contiguous dimesions.gc
+
+- [ ] transpose and flatten reduce dimeinsion to last user dimension. -- almost done.
+
+- [ ] NArray with 1-d index and md-shape??
+- [ ] enable a[a.sort_index] == a.sort for multi-dimensional array -- perhaps done.
+
+- [ ] specify Input/Overwrite array -- already has OVERWRITE
+
+- [x] accept int-array as index argument of aref.gc
+
+- [x] convert binary from/to Stringgc
+
+- [x] Complex#seq allows complex stepgc
+
+- [ ] Frozen array -- checking OBJ_FROZEN.
+
+- [ ] Marshaling -- perhaps done except Bit, Struct.
+
+- [x] inspect Enumerable#step objectgc
+
+- [x] contiguous checkgc
+
+- [x] propagate_nan for min,max,sum,...gc
+
+- [ ] parsing keyword arguments -- use ruby api.
+
+- [x] use erbpp2gc
+
+- [x] switch to TypedData.gc
+
+- [x] how to get the element size value effectivelygc
+
+- [x] introduce keyword :keepdims (keep dimension/axis) for reduce_dimension.gc
+
+- [x] refactoring array.c: avoid using na_compose_t and na_ary_composition.gc
+
+- [x] reshape!gc
+
+
+- [ ] flatten_dim
+
+- [ ] name of new_zeros, zeros_like etc.
+
+- [ ] NMath.sin => DFloat.sin ??
+
+- [ ] contiguous if na_view->stridx == NULL ?
+
+- [ ] store_binary with bite_swap.
+
+- [ ] write barrier?
+
+- [ ] move "reduce" field from RNArray to RNArrayView?
+
+- [ ] unify RNArrayBase and RNArrayView structure??
+
+
+- [ ] Thread-locked array??
+
+- [ ] use rb_thread_call_without_gvl??
+
+
+- [ ] alignment
+
+- [ ] force buffering option
+
+- [ ] update MT Random Number Generator
+
+- [ ] GVL release
+- [ ] Ctrl-C stop during method
+
+- [ ] floor method should be same as Ruby floor or C99 floor ??
+
+# constants
+
+- [ ] NAN
+- [ ] INF
+- [ ] EPS
+
+# Matlab method
+
+- [x] logspace
+- [ ] meshgrid
+- [x] rot90  
+- [x] rad2deg
+- [x] deg2rad
+- [x] expm1
+- [ ] histcount
+
+# from numpy
+
+- [x] <<,>> 
+- [x] swapaxis
+- [ ] squeeze
+- [x] trace
+- [x] ptp 
+- [x] clip 
+- [ ] ravel
+- [ ] take
+- [ ] put
+- [ ] choose choise
+- [ ] select
+- [ ] partition
+- [ ] searchsorted / bsearch
+- [ ] compress
+- [ ] pad
+- [x] tile
+- [x] copysign
+- [x] bincount
+- [ ] unique
+- [ ] roll
+- [x] repeat
+- [ ] logical_and/or/not - Bit & | ^
+- [ ] minimum,maximum
+- [ ] shuffle
+- [ ] interp
+- [ ] intersect1d
+- [ ] asarray  - cast
+- [ ] persentile
+
+# Math
+
+- [ ] csc,sec,cot
+- [ ] csch,sech,coth
+- [ ] acsc,asec,acot
+- [ ] acsch,asech,acoth