parse.y: fixed bison 3.0 warning

YACC  src/parse.y -> build/host/src/y.tab.c
src/parse.y:936.1-12: warning: deprecated directive, use ‘%pure-parser’
[-Wdeprecated]
%pure_parser
Merge pull request #1448 from cremno/bison-3.0-pure_parser-warning

fix bison 3.0 warning
add comments for major GC
Merge pull request #1449 from Fleurer/fix-comment-for-major-gc

add comments for major GC
remove duplicated incremental_gc_until() in generational GC; #1449
clean up the warnings when GC_PROFILE is on
def statement and define_method now return symbol a la Ruby2.1
Merge pull request #1450 from Fleurer/cleanup-warninigs

clean up the warnings when GC_PROFILE is set
Silence 'unused parameter' warnings
I fix ISO No in String class in comparison with ISO_IEC_30170_2012(E)-Charactor_PDF_document.pdf
move (void) cast after declarations
use CHAR_BIT instead of bare 8
Merge pull request #1458 from suzukaze/fix-iso-no-in-string-class

I fix ISO no in String class in comparison with ISO_IEC_30170_2012(E)
fix #1459

gen_vmassignment() missed a pop() in a conditional branch, but we have
to keep each conditional branch 's stack depth the same all the time
when it left execution.
Merge pull request #1460 from Fleurer/fix-1459

fix #1459
Merge branch 'master' of github.com:mruby/mruby
define Class#new in ruby to call #initialize
I add ISO test '15.2.12.3' included modules in Arrray
Merge pull request #1468 from suzukaze/add-array-test

I add ISO test '15.2.12.3' included modules in Arrray
ci->target_class should point to ICLASS, not MODULE; close #1467