v0.3.1

Changelog

ed62694 Add newline after CHAR_BIT definition in limits.h
cf3a7e7 Add windows stubs
ac40214 RAND_MAX (#15)
ce9b713 builtin: define ptrdiff_t and size_t; fixes #33
bd6831f constants
d4b2d9f cxgo: assign arg names automatically when only some are set
29aec51 cxgo: properly preserve unused expr statements; fixes #13
4952273 cxgo: require Go 1.16
121362e cxgo: use GetLibrary in more places; fixes #26
803c094 deps: update cc/v3
18fb1b5 libs/math: support fmod function
1d064da support typed strings
5b77c74 update parser
0435ecd update parser (#17)