Check pkg-config once and don't use it if it's not avaialble.
Fixed #313: index out of bounds error with a restriction that has an incorrect number of type vars
Fix typo in compiler commands
Merge pull request #315 from xiy/fix-command-typo

Fix typo in compiler commands
Added state parameter to OAuth2::Client#get_authorize_uri
OAuth2: get access token using client credentials, and some other small things.
Added some typeof specs to OAuth::Consumer
Small fix in OAuth::AccessToken
Fixed type inference bug related to NoReturn
Removed `src` and crystal compiler `libs` directory from CRYSTAL_PATH.