RFCT : finished edits to tool_args
pep8 : added line
RFCT : moved _all_subclasses to utils

modified imports accordingly
ENH : added available handler listing function
RFCT : renamed data_base -> handler_base

data_base is an astoundingly bad name for a module

(there are three hard things in CS: naming things and of by one bugs)
EXP : added example of how to use a tool
VCS : added binary file globs to .gitignore