Make Array#[]= raise IndexError.

If second param is negative, Array#[] raise IndexError.

Remove `Time` defined check in mruby-time gem test.

Fix build on mingw32/64: struct timeval isn't defined in default. See: 6...

Fix build on mingw32/64: struct timeval isn't defined in default. See: 642477ef

Implement Kernel.fail and Kernel#fail .

OP_ENTER fix variable assignment

Add a comment to ObjectSpace.each_object.

refactor fix_mod

fix unreachable condition
use b

Add functions for safe addition and subtraction

Implement day of week methods.

fix memcpy-param-overlap

Add Hash#keep_if

Refactor read_lineno_record_1() in load.c

Refactor string.c

Fix indents in mrb_str_inspect() of string.c

Use mrb_bool instead of mrb_int  in string.c

Add Hash#invert