Fix backend crash when the client encoding cannot represent a localized error message (Tom)

We have addressed similar issues before, but it would still fail if the “character has no equivalent” message itself couldn't be converted. The fix is to disable localization and send the plain ASCII error message when we detect such a situation.

Fix incorrect tsearch2 headline generation when single query item matches first word of text (Sushant Sinha)

Fix improper display of fractional seconds in interval values when using a non-ISO datestyle in an --enable-integer-datetimes build (Ron Mayer)

Ensure SPI_getvalue and SPI_getbinval behave correctly when the passed tuple and tuple descriptor have different numbers of columns (Tom)

This situation is normal when a table has had columns added or removed, but these two functions didn't handle it properly. The only likely consequence is an incorrect error indication.

Fix ecpg's parsing of CREATE USER (Michael)