Add configurable PS

[trashnroll]

No description provided.

[lig]

It will be very helpful.

Also it will be nice to have a bit more informational PS. Like current branch and/or uncommitted files count or whatever.

[alsmirn]

Fellas (@lig @trashnroll ), which more options is interesting besides:

• current branch name;
• current commit hash;
• fast-forward commits count?

[trashnroll]

maybe start with a copy of __git_ps1 options?

[lig]

@alsmirn current branch name and current commit hash should be same option. Branch name displayed if possible commit hash otherwise. It is called commit-ish afaik.

Color indication will be useful e.g. different colors for tracking and non-tracking branches, and/or for uncommited changes status.