Add postgresql prepared queries and stop relying on string formatting
for sql parameter passing
more precise word
Various fixes to how the Boehm GC's interface.

The Boehm GC interface did not define the getXXXSharedMem() functions
that were needed for compilation with --threads:on. It also used
`ppointer` instead of `PPointer`, so it failed to compile with
--cs:partial.
Merge pull request #1532 from PavelVozenilek/devel

more precise word
Merge pull request #1533 from rbehrends/fix-boehmgc-interface

Various fixes to how the Boehm GC's interface.
Merge pull request #1507 from idlewan/postgresql

Add postgresql prepared queries