(removed non-octave ... comments, added octave's # comments)

Closes #2268

Added a wrapper for js-yaml.js to enable YAML lint support. Followed
json-lint.js pattern. Unfortunately js-yaml.js only shows one error at
a time, but something is better nothing. Checked code with linter and
ran tests. All came back clean.

(Only works if anyword-hint.js is loaded.)

Doesn't take up any space now, so that a tab of width 2 is 2 em width
rather than 3.

Closes #2262

It apparently does not have a working buttons property on its mouse
events.

Issue #2260

The vim mode was making sensible use of a searchcursor with
a match-everything regexp as cursor.

Issue #2259

It doesn't do anything useful, and makes replace-all loop
forever.

Closes #2259

Issue #2256

... so that users can use \1, \2, etc in the replace expressions.

Issue #2253

relates to https://github.com/marijnh/CodeMirror/issues/314

Closes #2075

Issue #2182

Issue #2219

add docs that when completions are object they can have a from: and to:
that will be used by pick.

Make sidebar in manual scrollable for small screen especially usefull
when `Programming API` is unfolded

seem to look nice on Chrome and Firefox Osx, (scrollbar do not appear,
except when scrolling on Chrome) but should maybe be tested on linux.

It causes autozooming on some mobile platforms.

Closes #2235

... so that '|' can be used as an OR in regular expressions or as a literal
character, depending on whether it was escaped or not.

1) fix the escaping of '(' and ')' in search expressions.
2) get the correct placement of the '\' in characters that need to introduce escaping.
3) change the capture unit test to expect that '(' and ')' should be escaped, as does real vim.

adds escaping for '|' to bridge a difference between javascript and
vim regex flavors.

take the escaping a little lower level so that it affects '/' searches
as well, not just '%s/<regex>/<replacement>' searches.

So that calling it on a block in sequence won't get stuck with an
outdated state after lines whose indentation doesn't change.

Closes #2227

Closes #2225

So that it doesn't error when inner modes are missing.

Issue #2224

Previously commands like da<object> only worked with the opening side of the
pair, so you could do da{ but not da}.

I also removed some duplication of calls to selectCompanionObject (at the cost
of switching from map lookup to an if-else chain).

Issue #2223

So that the default mode when this is loaded first is actually a
working mode.

Also: indent the file to correspond to the rest of the codebase.

Closes #2223

Issue #2221

This fix has been modelled after the getMode function in runmode.node in
v3.20.0

(Border-sizing on the CodeMirror-linenumber class)

Issue #2210