improve/redo tsm screen

[ii8]

• [x] don't push things into scrollback unnecessarily when reducing size
• [ ] move things from the scrollback onto the main screen when increasing size
• [ ] don't cut off text at the right when decreasing size, instead wrap text properly as resize occurs
• [ ] allow special rendering for the cursor so it can have different shapes and colors
• [ ] fix selection behavior for empty cells left of text
• [ ] double and triple click select