Added test case for String#start_with? with string of length 1.
Fix for string-length-related issue in String#start_with? logic.
Added test case for String#end_with? with string of length 2.
Fix for string-length-related issue in String#end_with? logic.
Refactor of String#end_with? comparison logic.
Refactor of String#start_with? comparison logic.
add mrb_string_type().
Check type of arguments for #start_with and #end_with.
Merge pull request #1490 from take-cheeze/cxx_extension

support file extension .cpp/.cxx in mrbgem and tool
Merge pull request #1484 from fjmilens3/string_start_with

Bug in String#start_with? resulting from incorrect length determination
Merge pull request #1485 from fjmilens3/string_end_with

Bug in String#end_with? resulting from incorrect length determination
Merge branch 'mruby' into pr-typeerror-string-start-end-with

Conflicts:
	mrbgems/mruby-string-ext/src/string.c
	mrbgems/mruby-string-ext/test/string.rb
Remove function delarations not implemented in code
Merge pull request #1486 from iij/pr-typeerror-string-start-end-with

Crash if you call String#start_with/end_with with non-String arguments.
Merge pull request #1491 from dmajkic/master

Remove function delarations not implemented in code
Removed unnecessary #undef ISPRINT in include/mruby.h
Merge pull request #1492 from pbosetti/master

Removed unnecessary #undef ISPRINT in include/mruby.h
revert #1470; fix #1493
add Exception#backtrace test
fix crash in 2nd call to vsnprintf