Merge pull request #588 in G/fastr from...

Merge pull request #588 in G/fastr from ~LUKAS.STADLER_ORACLE.COM/fastr:feature/internals_rework to master

* commit '564543fb':
  imports, static, and various other cleanups
  small cleanups
  fix copyright years
  make “isatty” INTERNAL
  enable passing test
  additional profile in FilterNode
  use RTypes for fast paths, additional type profile in SetDiffFastPath
  additional profiles in vector extract nodes
  use voidExecute in loops
  fix “options” to always set visibility
  move .Internal handling to AST creation, remove ForcePromiseNode, keep RSyntaxElement instead of RSyntaxNode in RCaller