Merge cdiff into diff

[Daniel Clemente]

Coloured diff is nicer than coloruless diff for many users, and it has the option to disable it if the user doesn't want it. Therefore coloured diff could be the default one, and be available into „bzr diff“ with no need for bzrtools.

A good colour combination must be chosen, considering there are many colour blind for red/green, and that the colors must look nice (i.e. not only grey on white).

The colored diff could have --color=auto as default instead of --color=always, so that „bzr diff > file.patch“ doesn't produce garbage. „bzr diff --color=always | less -r“ would be used if you want colors in less (just like the GNU program ls: „ls --color=always | less -r“).

[Parth Malwankar (parthm)]

Bug #597626 - bzrlib should support color, is related.

[Robert Bruce Park (robru)]

Is there a way to configure what colors are used? I appreciate the default choice of blue/red because of the propensity for red/green colorblindness, however I personally have a very difficult time reading blue text at all, so I really need red/green text to reduce eyestrain.