Version 1.6.1

Restores support for the previous versioning system (pre 1.6; see #225), and fixes a number of issues with the new versioning system:

• Allow package name to differ from repository name (holoviz-dev/autover#39)

• Allow develop install to work when repository is dirty (holoviz-dev/autover#41)

• Fixed failure to report dirty when commit count is 0 (holoviz-dev/autover#44)