inline mrb_gc_arena_restore() and stack_extend() in VM loop
add mrb_intern_lit for creating symbol from string literal
Merge pull request #1600 from take-cheeze/mrb_intern_lit

Proposal of mrb_intern_lit macro.
Change scapa and rcapa to size_t, use scapa.
Merge pull request #1601 from carsonmcdonald/srcaptosizet

Change scapa and rcapa to size_t, use scapa.
should not access scope after releasing memory pool
avoid top-level pool release at codegen_error() and fixed some memory leaks
Add is_a? test to cover issue 1477
remove unnecessary keep size adjustment in stack_extend_alloc(); close #1602
Merge pull request #1604 from carsonmcdonald/1477isatest

Add is_a? test to cover issue 1477
Fix ISO no in Array#* and Array#+
Merge pull request #1605 from suzukaze/test-array

Fix ISO no in Array#* and Array#+
Fix mod.constants cannot return the single character constant
Merge pull request #1606 from bggd/patch-1

Fix mod.constants cannot return the single character constant
modify test case to check #1606
Avoid recursive instance variable inspections
Merge pull request #1607 from h2so5/avoid-recursive-inspection

Avoid recursive instance variable inspections
Fixed callinfo buffer overflow while calling ensure handlers
Merge pull request #1608 from nanamiwang/vmcrash

Fixed callinfo buffer overflow while calling ensure handlers
Update the INSTALL information to be more accurate