Add unit test for noremap.
Make map and noremap commands affect OMAP.

- in Vim, map and noremap commands affect normal,
  visual, and operator-pending mode
- see :help noremap in vim
- added the lately introduced OMAP to the list of
  KeyMaps changed by map and noremap
Merge pull request #397 from wawe/map-affects-operator-pending-mode

Map affects operator pending mode
Fix #394.  Handle search strings that end in backslashes.  Also, if
regexsearch is enabled, print error message when regex is invalid.
Oops.  Don't assume delimiter is '/' (also handle '?').
Update unstable update site.
Add toString in TextViewerPosition for debugging.

It can be hard to track position errors when you can't see where a
Position is pointing to.
Fix line-wise selection swap for CRLF line endings

A line-wise selection includes the bottommost newline. The original
code tried to calculate the last line of the selection by trying to
skip left past this newline, but this puts us in the middle of a CRLF
newline character when using Windows endlines (causing an Eclipse
exception).

Simply recreate selection based on the swapped from / to positions.
These can be anywhere on the first and last line, but that is enough
to recreate a line-wise selection anyway.

Fixes #392.
Remove pointless call.
Always clear selection when leaving visual mode.

Improve the original test to see if the selection is cleared when
leaving visual mode; there was no actual leave command triggered.

Test that entering command line mode from visual mode (thus using a line
range) will go back to normal mode AND clear the selection.

Tweak the commond parser to run an extra LeaveVisualModeCommand when
coming from visual mode to fix the latter test. Running it
unconditionally would have side-effects: quitting command line mode
without a selection would clobber the last selection marks and "gv"
command.

Fixes #399.
Keep cursor near selection end on visual mode exit

Vim will keep the cursor in the very same spot when exiting visual mode
whereas Vrapper would always reset the selection to the top- and
left-most point of the selection.

Try to reset the pointer to a point nearest the end of the selection,
accounting for reverse selections.

Note that this isn't correct for visual line-wise mode as the caret
can only be drawn at the end of a selection.