Merge pull request supercollider#1371 from supercollider/topic/fix-do…

…c-modified-warnings

ide: Fix triggering of doc modified signal

ide: Fix build, missing SC_BuildString function.

Last commit before pull request supercollider#1334, which switches ma…

…ster to QT5.

Commit of pull request supercollider#1334, which switches master to QT5.

Merge branch 'qt52' into scztt-sandbox

Jenkins Git plugin tagging with validated-linux

Minor enhancements after first rewrite

- Trying to be more balanced in version comparison.
- recommend supernova
- mention svn
- cosmetical stuff