add Float#nan?
Merge pull request #1678 from iij/float-nan-p

add Float#nan?
fibers cannot cross C function boundary; close #1680
Remove warning
Merge pull request #1682 from mattn/remove_warning

Remove warning
better codedump format
Fiber.new{break} caused SEGV
disable LocalJumpError test since the code causes SyntaxError (not LocalJumpError) on CRuby
add RUBY_VERSION to notify syntax compatible version
pass gem_flags_after_libraries
Merge pull request #1683 from take-cheeze/gem_flags_after_libraries

Pass forgotten variable gem_flags_after_libraries to tool's linker.run.
Add pluggable versioning by mruby-version
Fix release date
replace Kernel.show_version with MRUBY_DESCRIPTION
Add global constant MRUBY_COPYRIGHT
Fix MRUBY_BIRTH_YEAR
introduce mrb_str_new_lit() to create strings from C string litrals
use mrb_str_new_lit() more widely
remove unnecessary semicolon
Merge pull request #1688 from cubicdaiya/issues/unnecessary_semicolon

Remove unnecessary semicolon