Fix SQLite3 installer
Fix SQLite3 installer

The installer had a few problems:
1) It was using multi-value/multi-row INSERTs, something which are not supported by SQLite3
2) Double declaration of primary keys in some tables, causing them to be not created (and the installer would skip them thinking they're duplicates
3) messages table had incorrect definition for modified_reason column

Related to #40

Signed-off-by: Shitiz Garg <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@dragooon.net>

georaldc/SMF2.1,mkress/SMF2.1,margarett/SMF2.1,StealthWombat/SMF2.1-more-forkery,georaldc/SMF2.1,margarett/SMF2.1,mkress/SMF2.1,MustafaCan/SMF2.1,MustafaCan/SMF2.1,mkress/SMF2.1,StealthWombat/SMF2.1-more-forkery