Add handling of "-" as array index (Fix #23)
Merge branch 'hyphen_array_index_support'

Conflicts:
	src/json-patch-duplex.ts
conform to https://github.com/json-patch/json-patch-tests
remove invalid test (https://github.com/json-patch/json-patch-tests/issues/15)
move changelog to https://github.com/Starcounter-Jack/JSON-Patch/releases
0.4.0