Remove checking for missing wiki folders

Thus undoing 744245ea3249446fd15f504190efb1d828935d01 because of #1002
Coloured warnings and errors under Node.js
Add warning when serving a non-existent wiki folder

The warning will be yellow to make it noticeable
Report command errors through $tw.utils.error

So that we get the new colourisation
Use titles when dragging links to non-TiddlyWiki destinations

Handily, this means that you can drag tiddler links from the sidebar
into the text editor, making it easier to create links and
transclusions.
Move search result count logic out of translations

Also fixes a problem pointed out by @Evolena whereby the advanced
search counts hadn’t been adjusted to remove `$:/temp/advancedsearch`
from the search.
Add theme tweaks for body text size

Fixes #891
Ensure JS macros return text
Extend the view widget to work with subtiddlers
First pass at an edition for translators working in the browser

The user interface needs some refinements but it shows the basic
principles.

The idea is that the translator would email their modified file, which
would then be merged into the core repo (some additional tools will be
helpful for this).

Fixes #984
small typo on WidgetMessage: tm-add-field

You can read FieldMangerWidget instead of FieldManglerWidget. A single L is missing, so the links are not working properly.
Dev docs update
Merge pull request #1005 from danielo515/patch-1

small typo on WidgetMessage: tm-add-field
More fieldmangler typos
Add an advanced search toolbar button
Release note update
Hide advanced search toolbar button by default
Adjust wording of theme tweaks
Clarify warning
Docs tweaks