Sort rmgen functions by logic

[elexis]

The old school rmgen directory is a bit messy, because three of the files don't have a clear separation of functions according to logic:

• utilityfunctions.js contains some frequently used elevation and entity placement helpers.
  • The filename is arbitrary and should be renamed before random unrelated code is added there.
  • It could be split to terrain_helpers.js and placer_helpers.js or similar.
  • Its tileClass hardcodings can lead to reference errors and have to be removed.

• misc.js
  • contains some frequently helper functions for the starting base that should be moved to a new file startingentities.js. That file will be extended with new helper functions that will replace the duplication of the starting base code in every rmgen file.
  • contains some frequently used terrain and placer helper functions too.
  • contains a lot of linear algebra unrelated to any rmgen implementation and should be moved to a new file
  • contains some rmgen1 brand functions which are deeply connected to the code in constraint.js, tileclass.js and painter.js and hence should be moved there
  • contains the four modifyTilesBasedOnHeight functions. They could be either moved to the three files above or the other short global helpers which don't fit anywhere in library.js.

• library.js:
  • contains some starting base functions which should be moved to the new file.
  • contains some engine hardcodings, which should be replaced with an engine getter sometime (FeXoR ticket somewhere)
  • contains some useful short globals like fractionToTiles
  • contains a lot of silly proxies like sin = Math.sin and PI = Math.PI which should be deleted
  • contains some unrelated math helpers like getAngle or getDistance which can be moved to the new math file

After that, library.js will be about 100 to 200 lines of code only, misc.js and utilityfunctions.js deleted. So it will be easier for new readers to understand the rmgen library.