postgresql tweaking: move where normalisation of unsupported types (eg. mysql mediumtext) is done so it doeesn't cause needless schema recreation
postgresql tweaking: chomp index names to 63 characters (as postgresql itself would do) in the normalisation step so it doeesn't cause needless schema recreation
more postgresql tweaking: use 'real' instead of 'float' to get single-precision floating-point numbers, so they come back as single-precision from schema dumps