Implemented full-text search using SQLite's FTS4 extension.
FTS: Don't return text as key; it's now a separate .fullText property
FTS: Added API to get the match range(s) in the text.
FTS: Added support for snippets in the query rows.
FTS: Query results should be restricted to those from the view being queried!
FTS: Ranked sorting; header refactoring

* Implemented sorting by ranking (can be turned off for speed)
* Order and limit options honored
* Split FTS stuff out into CBLQuery+FullTextSearch
FTS: Text keys now denoted by CBLTextKey() rather than a special dictionary.
FTS: Improved language support by integrating Unicode Snowball tokenizer

Tokenizer from <https://github.com/illarionov/sqlite3-unicodesn>.
Supports Unicode, and stemming for many European languages plus Russian
and Turkish (see full list in file modules_utf8.txt)
working toward geo
begin running tests
first geo test is passing
Lots more work on geo stuff.

* Fixed some coding errors
* Use native structs instead of objects to hold points/rects
* Made bounds test (in SQL query) use half-open intervals
* Made unit test pass.
Switch to emitting geo point as the key in a regular emit() call.
Added public API on CBLQuery to do a bounding-box query.
GEO: Added support for bounding-boxes.

* Use CBLGeoRectKey to emit a bounding-box as a key.
* CBLGeoJSONKey now understands rects.
* CBLQueryRow now has a boundingBox instead of a geoPoint.
GEO/FTS: Minor fixes
GEO: Oops, GeoJSON doesn’t have a Rect type so I have to use Polygon.

Also moved all the geometry related stuff to CBLGeometry.h, a new public header.
GEO: Use SQLite R*tree. Preserve emitted GeoJSON geometry.

Also split out the geo query API into CBLQuery+Geo.h.
Updated the .exp file.
REST API support for geo & full-text queries

View query options for geo are:
 ?full_text= (FTS query string)
 ?snippets (true to enable snippets in output)
 ?ranking (false to disable ranked sort order)
Output rows will have properties "matches" and maybe "snippet".

View query options for geo are:
?bbox (JSON array of 4 numbers: [x0, y0, x1, y1])
Output rows will have properties "geometry" and "bbox".
FTS: Fixed value of “snippets” property in JSON/REST query row.