accesskeys: add whitespace to combine() for reasability
accesskeys: combine using correct case

We always thought, or claimed that we combined accesskeys based on
prefering the case before using an alternate case.

It seems that our code actually prefered uppercase and then would try
lowercase.  Thus this string:

"Close Other Tabs" combined with an accesskey of "o" would result in
"Close &Other Tabs" because capital O would win even though lowercase O
was present.  The correct combineation should have been "Cl&ose Other
Tabs", preferring the correct case before the alternate case.
docs: Add note to bump version up post release
Remove copyright statement (I abstain from any personal IP rights! Thanks for maintaining this. Dominic)
Revert "Cleanup: Use the @ syntax for some properties"

This reverts commit d211e0de47114d3e2b8bc31ef0f7f9fc24355fb5.
Revert "Cleanup: Rename isblank to is_blank and convert to property"

This reverts commit 199cf7926fffd5dd7ee1838cb0de0f97bf9032dd.

This gets us back to before we started altering the TTK API and deprecating
the changed methods.
Add deprecated decorator to easily mark deprecated functions and methods
Use the new deprecated decorator instead of custom deprecation code
Styleguide: combine parameter type and description

It looks tidier this way, and is allowed by
http://sphinx-doc.org/domains.html#info-field-lists.