drop non-alpnanumeric chars from Canonical Name

following up on #2659, further steps toward an algorithmic
derivation of Canonical Name from App Name.

Also add two rules about hyphens which are implied and already
followed by every Cask.
add "doutdated" example external command

it acutally does something useful, unlike my previous examples
doc that vendor/upstream URLs are preferred

(unfortunately adding words to CONTRIBUTING.md again)
quiet "move to applications" popup for github.rb
New cask: wowhead-client 1.2.2
Update Totalfinder to 1.5.19
Merge pull request #3244 from rolandwalker/github_move_suppress

quiet "move to applications" popup for github.rb
Merge pull request #3212 from rolandwalker/doc_vendor_url

doc that vendor/upstream URLs are preferred
Merge pull request #3190 from rolandwalker/example_cmd_doutdated

add "doutdated" example external command
Merge pull request #3251 from res0nat0r/wowhead-client-1.2.2

New cask: wowhead-client 1.2.2
Merge pull request #3252 from linc01n/totalfinder

Update Totalfinder to 1.5.19
Merge pull request #3175 from rolandwalker/doc_cask_name_drop_characters

drop non-alpnanumeric chars from Canonical Name
rename join-me.rb

to joinme.rb
per naming rules in CONTRIBUTING.md
rename tune-instructor.rb

to tuneinstructor.rb
per naming rules in CONTRIBUTING.md
Merge pull request #3254 from rolandwalker/rename_tune-instructor

rename tune-instructor.rb
Merge pull request #3253 from rolandwalker/rename_join-me

rename join-me.rb
Upgrade Hopper to v3
Add Nimbus (0.7.1)
Merge pull request #3256 from cHoco/master

Upgrade Hopper to v3
Merge pull request #3257 from dlackty/nimbus

Add Nimbus (0.7.1)