CodePrinter added to Printers 2.11.0

1. Typed trees printer is added to internal.Printers (as a part of CodePrinter). 
CodePrinter generates the code for passed attributed/unattributed trees.
2. Attributed val/var processing for syntactics is added (SI-8180).
3. Tests for CodePrinter are added.
4. Code cleanup for EOL-printing #3377

Previous version (with comments): #3481