Fix up format error introduced c6494fa18f941e578a2985af1c916b411a5a13c3
Rename config.setting.color_* to config.color.item_*

* Add a hook in tagger.py to handle this change
* Read config.setting.color_* values, store to config.color.item_*
* Delete old options
* bump picard version to 1.3.0dev1 to force config upgrade

It serves as a test case for the recently added config upgrade handling code.
Make tag status colors configurable (not yet through UI).