Update GUI-Layout-Management.schelp

I added example about the question why a UserView might not show up in a Layout.
netbsd: use compile-time OS flag, in same places as freebsd - thanks Thomas Klausner
netbsd: Add missing header for strerror() - thanks Thomas Klausner
lang: use proper interface to get position within File - thanks Thomas Klausner
netbsd: avoid referring to QGtkStyle, not a public symbol - thanks Thomas Klausner
build rules: neater check for Linux-or-*BSD, thanks Tim Blechmann
Classlib: PlotView: Don't post spec in calcSpecs
Build: travis.yml for main qt4.
plugins: onsets, fix potential issue with multiple unsequenced increments
Build: travis, use standard cmake (nonstandard is for qt5)
Merge pull request #1135 from jamshark70/topic/removeNeedlessPosts

Classlib: PlotView: Don't post spec in calcSpecs
help: fix typo in README
update tutorial
ide: dumpOSC is updated in GUI. Issue #1136 remains unfixed though.
class library: merge now returns the class of the receiver. This fixes #1142
class library: no startup post for GeneralHID if not necessary. This fixes #1120.
class library: adjust code format
plugins: TrigControl behaves like Control. Fixes #1145
class library: adjust code format fix
class library: adjust code format