support c++ exception
fix compile error
add cxx_abi travis test
fix compile error of min/max macro
move jmpbuf_id to generated file
name c++ abi build
use g++ to link
revert wrong build_config.rb
wrap scope with do {} while()
define __STDC_* macros in y.tab.cxx too
define mrbconfs on all compiler
clear exc_catched before jumping to L_RAISE
add const to char* to pacify warnings for string litral to char* conversion
wrap function prototype by extern "C"
allow command like "ccache gcc"
use c++ compiler to link when c++ abi is enabled
use shallow clone in git gem
remove explicit use of g++
Merge pull request #1777 from take-cheeze/command_improvement

Command improvements.
Add ssh protocol support for bitbucket.