reword prepere() error. Fix for tableExists. Bump for 2.6 release

fixes

Adding support for mysql error codes

fixed missing space before operator when comparing against NULL

- added missing space ' '  befor appending operator to query in _buildCondition() default statement for NULL comparison
- changed shorthand php `<?` to default `<?php` in dbObjectTests for better downward compability

Update readme.md

- Fixed broken link
- Removed duplicate entry in TOC (Raw)

issue #375.  onDuplicate returns false when there was no change in data

update readme on correct null checks

commit() and rollback() methods should return results #41

fix a typo

fix $obj->relatedObj === null when not exists

Merge branch 'master' of https://github.com/joshcam/PHP-MySQLi-Databa…

fixes

clean code

dbObject - Join Method add primaryKey as var

fixes