Ugit improvements

[StartAutomating]

0.3.1:

• git help --all now returns as objects (Fixes ugit should extend git help --all #88)
• (git log .\filename).Diff() now only diffs the selected files (Fixes git.log.Diff() should be able to get diffs of a specific filename #87)
• git -C is permitted in any direectory (Fixes git -C should be permitted in any directory #85)

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