~axvr/ascribe.vim unlisted

Allow Ascribe to detect empty attributes

Previously the following attribute would have been ignored by ascribe.

    *.txt       foo=

Now it will save the value of 'foo' as an empty string.
Make Ascribe behaviour user-modifiable and easily extendable

This change adds a 'b:attributes' variable to each buffer. This variable
contains the list of attributes reported by Git for that file.

Also introduced is the 'g:ascribe_handlers' dictionary. This dictionary
defines the attributes which should be checked (as keys) and maps them
to an appropriate attribute handler (given as a 'Funcref').
Fix indentation behaviour when 'expand-tab' is disabled

Previously when 'expand-tab' was explicitly disabled, Ascribe would not
respect the user's chosen tab width.
Initial version