Remove database timezone handling by rolling back to previous version that used offsets instead. Based on problems noted in #218479 and #220663, we cannot count on database timezone handling to be available in MYSQL or work consistently with the timezone names that PHP uses in POSTGRES, so trying to do timezone conversions in the database is not going to work.

Synch with D5.2 version.

#218479 Add more information about db timezone support to the INSTALL.txt file and move the requirements test to the Date Timezone module.

More work on creating a 5.2 branch with an improved Date API that uses PHP 5 date functions. Includes beginnings of a date_repeat module and much improved ical parsing. Not ready to use yet, more work to be done.

Very preliminary rewrite of Date API to become version 5.2. Not ready to be used yet! Still coming is rewrite of date and calendar module to use new API.

Get rid of embedded help text and point to d.o handbook page instead to make it easier to keep it current.