case : plugin to case selected text

[RichardKelters]

Five functions to case selected text. (I'm fairly new with Github so excuse if I did not follow protocol correctly)

[rxi]

Looks good! a couple of points:

• You can add all the commands with a single call of command.add and one table with all the functions in it
• upper and lower are already provided by core (doc:upper-case, doc:lower-case)
• The alt+l shortcut conflicts with the default root:switch-to-right command

[RichardKelters]

Hi rxi,

Thanks for this review. I'm new to lua and did not notice the available functions, will make some changes later.

Richard