Add missing keyboard shortcuts related to segment commenting

ALT+C does not work at all. It should work in all editor modes - and even on locked segments, if commenting locked segments is permitted.

When cursor is inside the comment field:

• jump back to the opened segment on ALT+C  in SimpleMode → Close and save.
• enable save button of comments in simple mode to close the comment window
• Save comment and segment and open next segment in workflow on CTRL+ENTER
• CTRL+S and CTRL+ENTER are not working on commenting non editable segments
• Using CTRL+S in simple mode works only with an opened segment, but then the segment and comment is saved but the window remains open
• When saving a comment with segment open in row editor, the autostate is getting broken (text instead icon)

While fixing the above issues, some other issues were fixed:

• saving a comment with CTRL+S saves the segment and the comment, and disables then the metapanel. So the comment form is masked but is not really readonly, indeed it contains the focus and content can be typed
• Clicking the comment icon in the segment grid alters between opening the comments (desired) and normal meta panel on each click
• Comment Icons are not visible in ergonomic mode with enabled comment column
• ALT+C in simple mode opens one comment window on each press