* First pass at modular wiki indexes
An exploratory experiment
* Fix tests
* Faster checking for existence of index methods
We don't really need to check the type
* Use the index for the has operator
* Fix typo
* Move iterator index methods into indexer modules
Now boot.js doesn't know the core indexers
* Fix up the other iterator index functions
* Fix crash with missing index branch
* Limit the field indexer to values less than 128 characters
* Fallback to the old manual scan if the index method returns null
* Sadly, we can no longe re-use the field indexer to accelerate the `has` operator, because the index now omits tiddlers that have field values longer than the limit
Still need to make the index configuration exposed somehow
* Rearrange tests so that we can test with and without indexers
We also need to expose the list of enabled indexers as a config option
* Test the field indexer with different length fields
So that we test the indexed and non-indexed codepaths
There are other ways we could add maths to TW5 (including @EvanBalster's awesome https://github.com/EvanBalster/TiddlyWikiFormula) but the approach here has the merit of simplicity because it reuses the existing filter evaluation mechanism. That means that it's not ordinary "2+2" maths, it's a unique list processing language...
Docs to come
Fixes#254
* Fix search method for search tokens spread across fields
Addresses GH #3636, which reports that if you're searching for "test
body", and "test" only appears in the title field, and "body" only appears
in the text field, 5.1.18's search method won't yield that tiddler as a
result, which appears to be a regression from the 5.1.17 behavior
* Add test for searching for multiple tokens across fields
Verifies GH #3636:
> If I create a tiddler in the empty edition with the title "Test tiddler" and content "Body content", searching the wiki for "test body" yields no results under either "title matches" or "all matches". Searching for either word individually turns up "Test tiddler", and repeating this in an empty wiki I created from the 5.1.17 tag causes "Test tiddler" to show up under "all matches".
* Added better handling for sortByList manual placements
If manual placement specifications show up in an inconvenient order,
sortByList, will go to the trouble of processing them in that order.
* Added tests to confirm solution to (#3296)
...That custom tag ordering will not choke when tiddlers get sorted after their dependencies have been placed around them
* Corrected list-after bug when referencing external titles
* Using more error-proof $tw.utils.hop in sortByList
* minor indentation correction in test-tags.js
They don’t get automatically decoded when the browser reads the
resulting HTML. So, instead, we’ll solve
1e9e1a1fdc by switching to double quotes
for attribute values.