clone repository, remote picker and history improvement

List of changes:

- Added **clone repository** feature, it lets users clone an existing repository into the project folder
- Added **remote picker** feature, it lets users pick the remote to use on push/pull
- Now **history** button has two labels "Show history" and "Hide history" depending by the state

Currently the **remote picker** doesn't allow to add new remotes but I'd like to implement it later.

Hope everything it's okay.