Remove deprecated raster functions

[komzpa]

​https://postgis.net/docs/RT_ST_SummaryStats.html :

The ST_SummaryStats(rastertable, rastercolumn, ...) variants are deprecated as of 2.2.0. Use ST_SummaryStatsAgg instead.

​https://postgis.net/docs/RT_ST_MapAlgebraExpr.html

ST_MapAlgebraExpr is deprecated as of 2.1.0. Use ST_MapAlgebra (expression version) instead.

There are probably others.

[Darafei Praliaskouski <me@…>]

In 5aca2cb3/git:

ST_Mem_Size was removed, now from doc too

References #4214

[Darafei Praliaskouski <me@…>]

In 4d1c8d8/git:

locate_between_measures and locate_along_measure are deprecated

References #4214

[Darafei Praliaskouski <me@…>]

In 151c1150/git:

postgis_svn_version is deprecated

References #4214

[Darafei Praliaskouski <me@…>]

In 313a71a3/git:

ST_Count(rastertable, rastercolumn, …) variants removed

References #4214

[Darafei Praliaskouski <me@…>]

In d159dcf/git:

Remove ST_SummaryStats(table) and its derivatives

References #4214

[komzpa]

ST_MapAlgebraExpr remove looks heavy so pushing it to 3.2.

[komzpa]

good enough.