Fix launcher and some other issues

[kyechou]

Major changes

• Restructure the leagueoflegends script, removing unneeded variables/functions
• Abort the installation if an error occurs.
• Add install command to install a new LoL instance. It does nothing if it's already installed.
• Add uninstall command to remove installed LoL instance
• Fix launcher, tested on Arch Linux with wine-3.21
• launch command reports error and exits if LoL is not installed.
• Change the commands a little bit
  • regen_wine_prefix --> regen_wineprefix
  • launcher --> launch
  • Remove tail, since the log files are not used anyway. Logs are now printed to the standard output. One can redirect the output to any file if needed.
• Fix duplicate slashes in a better way
• Add vcrun2017 verb via winetricks
• Add a registry enabling MouseWarpOverride.
• Change msvcp140 from "b,n" to "n,b" (try native first)
• Install the GPLv3 license

Note for AUR packaging

lib32-libpulse and lib32-openal are necessary for the client to launch successfully. (#35)

Test result

I've only tested on Arch Linux with wine-3.21 and wine-3.21-staging, installing a new instance, logging into my account, starting a new game, losing it, and exiting the client. Fresh install works correctly, the league client can be launched either through terminal with command leagueoflegends launch or through the .desktop entry (#31), and it runs smoothly without crashing or noticeable errors throughout the game (#29, #36, #37). The installation process took about 5 min for each fresh install, although it may be affected greatly by the Internet speed or other networking factors. After the install, it took about 10 min for the client to update. Note that the default environment is win7 for the wine-3.21-staging instance in my laptop, and it works for both win7 and winxp. I haven't tested other environment settings though. (#26)

[kyechou]

I didn't update the README, since you may want to test it out before updating it.

[nefelim4ag]

As i just have no spare time to maintain package and code, i glad to see someone try make that work =)

Overall LGTM