Fallback to the term slug if a label does not exist in list-table

Relates to #214
A lot of code formatting
Remove extra space
Get title from parent object instead of get_the_title
Merge pull request #314 from x-team/issue-303

Get title from parent object instead of get_the_title
Release notes for 1.2.9
Version bump to 1.2.9
[issue-312] Check `live updates` checkbox by default
[issue-312] Make live updates enabled by default in Ajax callback
Yoda conditions
[issue-309] Add `get_changed_keys` method
[issue-309] Doc for new method
[issue-309] Return difference of arrays
[issue-309] Remove numeric indexes
[issue-309] Treat missing keys as differences
[issue-309] Add method to log theme modifications
[isue-309] Use updated option calback
[issue-309] Use improved keys comparison method
[issue-309] Add translations to header mods
[issue-309] Pass context as argument