Remove unused test setup
Call `#set_property_width_option` in unit tests
Fix `(1 ago)` in branch list for old branches
Note `(1 ago)` fix in history
Simplify `SystemExit` specs
Exit with non-zero if bad option (GH-27, GH-28)
Remove comment
Clarify variable name
Add `Branch.validate_property_name`
Simplify property name lookup
Make `property` a reserved branch property name
Note `property` as reserved name in history
Fix history item prefix
Remove extra hash instance
Initialize `options[:property_width]` once
Support `set_option(:property_only_name)`
Support `set_option(:property_except_name)`
Simplify `set_option(:property_{except,only})`
Simplify `set_option(:unset_property)`
Support `except-property` in config file