timeline: make sure not to set a negative size on elements.
render: Play the rendered file without blocking the UI
Finnish translation update
Updated Spanish translation
Updated Chinese (Taiwan) translation
Updated Russian translation
help: move medialibrary.page to index#gettingstarted
help: move welcomedialog.page to index#intro
help: move mainwindow.page to index#intro and delete interface.page
help: overall improvements in effects.page
help: overall improvements in keyframecurves.page
help: overall improvements in trimming.page
help: rename effectsanimation.page to usingeffects.page
help: move Configuring effects section from effects.page to usingeffects.page
help: add Effect Library section to usingeffects.page
help: add Animating effects with keyframes section to usingeffects.page
help: update meta info in usingeffects.page
help: create transitions.page
help: copy section from crossfading.page to transitions.page and update it
help: copy section from fadeinfadeout.page to transitions.page and update it