Fix infinite loop on drawing of large labels (almende#3228)

* Code cleanup, for better understanding

* Further refactoring; text processing to blocks in separate method

* Added unit test for labels - tests standard text and html tags

* Labels added unit tests for markdown

* Further refactoring; made multi and regular handling more congruent

* Interim save, not there yet

* Unit tests done, first working version

* Added test case with two big words

* Code cleanup

* Break up huge words into lines.

* Restore unrelated code change