- plugins: don't add hidden plugins to usermenu; ...

... use CPuginsExec::exec() to execute and drop CUserMenu::exec()
Merge remote-tracking branch 'cool-cst-next/cst-next'
- plugins: Fix assignment of prefered keys

New keyword in plugin.cfg: key=<key>
* key=red
* key=green
* key=yellow
* key=blue
* key=auto

If entry is missing key is auto-assigned
- user_menue: allow colored keys from plugin.cfg
Merge remote-tracking branch 'cool-cst-next/cst-next'

Conflicts:
	src/gui/user_menue.cpp
- user_menue: fix wrong changes in 19f7e04c77bf30f83324e98e23b74dc0611c3cef
Merge remote-tracking branch 'cool-cst-next/cst-next'

Conflicts:
	src/gui/user_menue.cpp
- user_menue: minor optimizations
- CPluginsExec::exec(): show possible script output
- pluginlist: use keyhelper to get hotkeys; allow colored keys from plugin.cfg
Merge remote-tracking branch 'cool-cst-next/cst-next'
Merge branch 'master' of https://github.com/MaxWiesel/neutrino-mp-cst-next