Update the signature for ST_X_Y_Z_Max_Min
Replace DOUBLE by double
Add table_of_functions template; start using it

In order to avoid having to maintain the tables of functions every time
we add a new function, I decided to do it programmatically using the new
table_of_functions template.

In this commit I demonstrate how to use it in
h2spatial-ext/affine-transformations. The following commits will move
the descriptions to the corresponding files.
Add images for ST_MakePoint
Update aggregates
Merge pull request #99 from gpetit/st-coord-update

Update the signature in ST_XMax, ST_XMin, ST_YMax, ST_YMin, ST_ZMax and ST_ZMin.
Replace POINT by double
Update h2spatial-ext/geometry-conversion
Update image n°2 for ST_MakePoint
Update geometry-creation
Update distance-functions
Update h2spatial-ext/predicates
Update h2spatial-ext/properties
Update h2spatial/geometry-conversion
Update h2spatial/operators
Update h2spatial/predicates
Update h2spatial/projections
Update h2spatial/properties
Add empty description variables
Merge pull request #101 from gpetit/st-makepoint

Add images for ST_MakePoint
Merge pull request #103 from agouge/template-function-tables

Add table_of_functions template