base: implemented guess_dependency
README: added qt5-qtbase-gui dependency
base: conf attribute is public
conf: exludes are default empty list
plugin_engine: removed warnnings in load_plugins
Implemented MakePlugin (Fix #54)
Implemented basic PythonPlugin (Fix #13)
Added PythonPlugin tests.
Implemented MakePlugin test.
command: added comparison
Renamed Command 'append_cmdlines' method to 'append'. (Fix #69)
test_plugins: fixed test_find_files