remove unnecessary depedency in test build
object_id may not return Fixnum (ISO says Integer), since intptr_t may be bigger than Fixnum, so type check for Numeric; ref #1630
Test case statement with splat
Merge pull request #1640 from carsonmcdonald/splatwhentest

Test case statement with splat
execute ensure clause correctly without OP_EPOP
avoid decrimenting eidx out of ecall()
need not to initialize ci->err at toplevel
Test for raise in ensure
Merge pull request #1643 from take-cheeze/remove_unnecessary_depedency

Reduce unnecessary mrbgems full test rebuild.
Merge pull request #1644 from carsonmcdonald/testraiseinensure

Test for raise in ensure
tests for "case" expression.
adjust proc->target_class according to surrounding proc->target_class; based on a patch from @Fleurer; close #1627
small cosmetic variable renaming
small refactoring (dedup mrb_vm_cv_set)
Merge pull request #1645 from iij/pr-case-expression-test

tests for "case" expression.
Merge branch 'master' of github.com:mruby/mruby
Add mruby-string-utf8
Merge branch 'mruby-string-utf8' of https://github.com/mattn/mruby into mattn-mruby-string-utf8
mruby-string-utf8: UTF-8 string may contail NUL; #1646
mruby-string-utf8: redefine String#size for UTF-8 string; #1646