mcolor: Add coloring support for diffs

[thyssentishman]

Add coloring for diffs sent as part of the email body. This adds support for the following three ENV variables:

• MCOLOR_DIFF_I: For (I)nserted lines.
• MCOLOR_DIFF_D: For (D)eleted lines
• MCOLOR_DIFF_R: For file (R)anges

Since the default theme is quite bright, these default to bright colors as well (Green1, Red1 and Yellow1 from the 256 XTerm colors respectively).

[leahneukirchen]

Almost out of scope for mcolor, but it's a cute feature.

I think there are other ways to end a unified diff, probably any line not leading with space, -, + should be regarded as end of diff?

[leahneukirchen]

hm, but git has the index lines...

[leahneukirchen]

I guess resetting diff on empty lines is good enough!

[thyssentishman]

Almost out of scope for mcolor, but it's a cute feature.

Glad you like it :)

I guess resetting diff on empty lines is good enough!

Updated, thanks!

[leahneukirchen]

I think less bright is better tho, make it 160 and 40.

[thyssentishman]

I think less bright is better tho, make it 160 and 40.

Yeah that seems better. Updated.

[thyssentishman]

Thanks :)