ref #12 start canvas export configuration
* add size functionality to export gui
* change ownership and interface of exporter (used now in viewer)
* add short keys for screenshots
* add advanced option to viewer
ref #12 export gui way works
* fbo resize does not work again
ref #12 fix capture
* introduce new interface to solve resize issue fixed in #19
* disable continous updates
ref #12 make presets workin
ref #12 add full restore support
* restore last config if custom
* restore last preset
* differentiate advanced caputure from direct capture
* increment filenames on direct capture
* resolve missing settings on first usage