installer: better defaults
installer: restructure to functions for each component setup

note: database setup needs only setup file to be written
installer: use common db class in installer as well
update-database: have single exit point from code, use exceptions
setup: invoke update-database in setup context

this preserves existing db connection and integrates better
drop changes.sql, we maintain db with "patches" (see upgrade dir)
move db setup schema to upgrade dir
setup: table prefix handled by db layer
setup: separate drop and create statements
drop.sql: sort lines
drop.sql: add missing tables
update release instructions
setup: use update-database to setup initial schema
drop upgrade/init.php, there's only one script doing db upgrades now
db upgrade: drop wrapper functions, expose $db and $dbconfigs to patches
patches: use query placeholders
Merge pull request #21 from glensc/setup

setup improvements