Merge branch 'develop'
Fix omnisharp-rename-interactively crashing

It would complain "all-solution-files is not a symbol".
Presumably the variable is not accessible to tags-query-replace when
tags-query-replace is evaluated. So I made the variable a global
variable instead. I don't like globals at all, but at least now it
works.
Improve function argument naming
Add Cask file
Setup tests for Cask