For cheaply adding extra styling without going over
the whole document and doing markText.

Issue #1069

* and # will fall back to non-blank characters if no keyword is found.

Issue #1065

- Fix bug where visual mode cannot be entered from EOL.
- When already in characterwise visual mode, pressing Shift-V now enters linewise visual mode instead of exiting visual mode.
- Mouse selection in normal mode enables visual mode.

`markText` changed parameters from v2 to v3

Various other style fixes. Updates to comments.

    Use newlineAndIndentContinueComment by default, falling back to newlineAndIndent if the former command is not defined.
    Same behavior is made default for Enter key in insert mode.

moveByLines was changed to better keep track of the previous
action.  For example, if moveToEol was the previous action,
moving up or down should stay at Eol regardless of line length.

See discussion in https://github.com/marijnh/CodeMirror/pull/984

As a die-hard vim addict, long ago, I retrained myself to type Ctrl-[ to
leave insert mode. This sends the same control sequence as escape in
many other places, actually, and this patch brings this functionality to
CodeMirror.

From vim's :help ctrl-[

                                        *i_CTRL-[* *i_<Esc>*
<Esc> or CTRL-[
    End insert or Replace mode, go back to Normal mode.
    Finish abbreviation.
    Note: If your <Esc> key is hard to hit on your keyboard, train
    yourself to use CTRL-[.

Typing CTRL-[ is particularly easy when caps-lock is remapped
to being another CTRL key, since now neither hand needs to move away
form the homerow, and both little fingers just slide a little, the left
little finger slides to the right to where caps lock used to be, and the
right little finger slides a little bit up to the '[' key

The 'inverted' hack which hailed from the ancient times when selection
was handled by the hidden textarea, has been replaced with a saner explicit
anchor and head. setSelection now directly sets the anchor and head, rather
than always creating a forward selection.