Fix df_keybind typo
Improve df_keybind

* Added additional options for joining keys and replacement text
* Made error message more specific
Update README (df_keybind)
Merge remote-tracking branch 'asvae/master' into asvae-master

(Merge asvae/master into lethosor/asvae-master)

Conflicts:
	Readme.rst
Update Readme.rst

Reformat first two sections (df_type and df_keybind)
Merge pull request #3 from lethosor/asvae-master

df_keybind updates