Document sfcgal functions and amendment notes for existing

[robe]

Olivier,

Since this will be installed as a separate section. You need to put all the functions in a new xml file. Lets call it reference_sfcgal.xml.

You need only document the extra functions that are not being swapped. HOWEVER for functions whose behavior switches from using GEOS/PostGIS in-built to SFCGAL, you need to note it in the docs.

Also you'll need to update the installation section so people know how to configure and compile with it.

You can also optionally add another using_sfcgal_dataman.xml

Maybe we can title it Using Advanced 3D or something.

Documentation doesn't have to be in place for 2.1.0 beta (thought would be nice to at least have an installation update). HOWEVER it has to be in before we go into final 2.1.0 release. This is why I've marked this as a blocker.

[robe]

I'm thinking for flag we can use:

 <para>&sfcgal_enhanced;</para>

To denote that if PostGIS is built with sfcgal, this function has enhanced functionality and will also make it easier to pull out functions for specific sfcgal garden stress testing.

[colivier]

Have been done:

• Documentation prototype to each new functions (reference_sfcgal.xml + st_force_sfs)
• Add sfcgal_enhanced flag on each function provided by both GEOS and SFCGAL
• Put 2 XSL files to handle SFCGAL comments and cheatsheet (didn't really check the cheatsheet output)

So enough to launch the garden test and to check every regress stuff based on Docbook documentation

Still to be done:

• Enhance/write the SFCGAL documentation (installation, backend, function examples…)

[robe]

All the SFCGAL functions have a bit of documentation. Enough for 2.2. So I consider this done.

I'll try to fill in some examples as I test, but by no means a showstopper anymore.

[robe]

Put in an example for ST_MinkowskiSum at r14036