Visual mode: added "Look Through Selection" action (default key is "Y"). This...

Visual mode: added "Look Through Selection" action (default key is "Y"). This action places visual camera at the same position as selected/highlighted thing and rotates it to match thing's angle. Special handling is available if targeted thing is AimingCamera, MovingCamera or SecurityCamera.
Script editor: pressing "F1" now opens keyword help instead of program manual.
Linedef edit form, Thing edit form: rewritten script support logic. It should now work in the same manner as the rest of controls.
Thing info panel: thing arguments now have proper labels.
Edit forms, UDMF: fields, which are handled by UI, are no longer shown in "Custom" tab.
Visual mode: fixed a crash when loading a model on a video card without Shader model 2.0 support.
Fixed incorrect argument number and changed most of labels in "Cameras and interpolation" section of zdoom_things.cfg.