replace PEAR::DB

[Elan Ruusamäe]

i was trying to fix bad backtrace when db was down
https://github.com/eventum/eventum/commit/9535ee4b6ed22da9a279e2855a5c5c5f3f434cf6

and realized, that it's impossible to fix it. the db layer needs to be replaced

as we use raw sql a lot ourselves, find some library that uses PDO, or just use PDO directly? probably should target php 5.3, as other pear libraries may not cope well with newer php versions

[Elan Ruusamäe (glen666)]

i've went over list of packages matching "PDO" in packagist repo
https://packagist.org/search/?search_query[query]=pdo

and come up with a list based on their description:
- https://github.com/lichtner/fluentpdo
- https://github.com/FractalizeR/phpSweetPDO
- https://github.com/mikehenrty/thin-pdo-wrapper
- https://packagist.org/packages/aura/sql
- https://github.com/auraphp/Aura.SqlQuery
- https://github.com/gajus/doll
- ...

[Elan Ruusamäe (glen666)]

- https://github.com/eridal/prelude-database
- https://github.com/auraphp/Aura.SqlSchema
- http://dbwebb.se/opensource/cdatabase requires php 5.4
- https://github.com/jstayton/Miner
- http://mardix.github.io/VoodOrm/ php 5.4
- https://github.com/fridge-project/dbal-docs/tree/master/book - not well documented
- ...

[Elan Ruusamäe (glen666)]

bridge code has been made, experimental Yii2 adapter works too.