Blender Git Loki

Bugfix [#29212] Select before/after current frame deselects all channels in
graph editor

No need to deselect all channels when doing the select left/right operator,
since we don't replace the selection afterwards with anything useful. This would
be a problem when the "Only Show Selected" option is enabled (as it is by
default), as this results in the curves being worked on disappearing from view.

F-Curves though will still get deselected as a result of the code to deselect
keyframes. Will need to review whether this is still a good idea (original
intention was so that only curves with keyframes selected would remain
selected).