Calculate # of semaphores correctly with --disable-spinlocks.

The old formula didn't take into account that each WAL sender process needs
a spinlock. We had also already exceeded the fixed number of spinlocks
reserved for misc purposes (10). Bump that to 30.

Backpatch to 9.0, where WAL senders were introduced. If I counted correctly,
9.0 had exactly 10 predefined spinlocks, and 9.1 exceeded that, but bump the
limit in 9.0 too because 10 is uncomfortably close to the edge.
Fix crash on compiling a regular expression with more than 32k colors.

Throw an error instead.

Backpatch to all supported branches.
psql:  fix startup crash caused by PSQLRC containing a tilde

'strdup' the PSQLRC environment variable value before calling a routine
that might free() it.

Backpatch to 9.2, where the bug first appeared.
Improve documentation about the relationship of extensions and schemas.

There's been some confusion expressed about this point, so clarify.
Extended version of a patch by David Wheeler.
In isolationtester, retry after EINTR return from select(2).

Per report from Jaime Casanova.  Very curious that no one else has seen
this failure ... but the code is clearly wrong as-is.
Update the description for the graphical installers

Remove references to "one click", as we're not supposed to call
them that anymore.
Merge remote-tracking branch 'origin/REL9_2_STABLE' into mdv92