Removal of new split view feature

[JEmlay]

Sure, you can turn off split view globally but for those that don't want to run around always turning off features, here's the needed code to hide it for tab-context.css:

#tabContextMenu #context_ungroupSplitView, /* Ungroup Split View /
#tabContextMenu #context_moveTabToSplitView, / Move Tab to Split View /
#tabContextMenu #context_separateSplitView, / Separate Split View /
#tabContextMenu #context_separateSplitView + menuseparator, /******* Separator *******/
#tabContextMenu #context_moveSplitViewToNewGroup, / Move Split to New Group /
#tabContextMenu #context_addSplitView, / Add Split View /
#tabContextMenu #context_openInSplitView, / Open in Split View */

I wasn't entirely sure which exact ones were needed so I just nuked them all.