rename MRB_ARGS_XXX to MRB_ASPEC_XXX; ref #1206
put MRB_ prefix before ARGS_XXX macros; ref #1206
add new functions to check if symbols are interned without registration.
rename every ARGS_XXX to MRB_ARGS_XXX; ref #1206
modify the type of return value (mrb_bool => mrb_value).
modify functions to suppress symbol registration into intern pool.
add new macro MRB_ARGS_ARG(n1,n2) to specify required and optional arugments at once
remove too many paren; ref #1209
aspec bits should be packed in Ax; ref #1209
a string may have a lot of non-printable chars.
fix Module#ancestors and update test
Merge pull request #1210 from iij/pr-inspect-many-non-printables

String#inspec & String#dump may raise an "arena overflow" error
Merge pull request #1211 from skandhas/pr-fix-Module-ancestors

fix the behavior of Module#ancestors
remove calling sprintf(); ref #1210
Move regression test as String#dump is not in ther core but the mrbgems.
Add tests to make sure. As we do not use standard library for formatting.
Remove sprintf().
suppress intern inside of 'respond_to?'.
Fix underlying memory leaks. When realloc is failed, memories are leaked.
More strict NULL checks.