Fix a version text (Rewrite update check) (#290)
    
    * Rewrite update check

    

    Before release, the update URL will need to be changed to an official

    one.

    

    * remove syntax macros: CASE, __OR, and DEFAULT

    

    * define VC_EXTRALEAN

    

    * modify the URL of opentoonz-version.txt

    

    * fix a type of updateUrl

    

    * remove meanless comments