Import options_parser
Fix to_error in taker.
Make clang-format happy
Check in Maybe.apply and report error in value
Move headers to sub directory
Fix gather
Import apt, wrapper for apt-get and apt-cache auto.
Make g++-4.6 happy
Check a command is given before execvp.
Add some options from apt-get and apt-cache.

TODO: How to solve the common options in get and cache?
Try apt-get and apt-cache after combined apt failed.
Add wordexp and parsing of string, lines and file
Add README
parser's priority is int.
Fix the multiple definition problem.
Add splited header files
Split arguments to dcl, inc and impl.
Split converter to dcl inc and impl.
Split document, matcher

Add string routins to string.h
Fix a warning.