Release v1.3.0

This release contains an implementation of Conventional Commits Suite kindly contributed by @serverwentdown. We've decided to make this the new default recommended suite for mkcommit, since it more closely adheres to the Conventional Commit guidelines than the pre-existing semantic suite. The documentation has been updated accordingly.

Pre-existing suites now also define a default() function which generates a tuple of the first line and the body of the commit message. Hence a new concise pattern can be used when creating a CommitMessage instance:

from mkcommit.suites import conventional

def commit():
    return CommitMessage(*conventional.default())

Also, the implementations of default_long, which are called from default, will trigger the default system editor for the developer to provide a longer message when necessary.