Some structure.sql fixes
Some structure.sql fixes

1. Duplicate table `edited_message` removed
2. In MySQL 5.7 with default mode `STRICT_TRANS_TABLES` you can see error: `SQL Error 1101: BLOB/TEXT/GEOMETRY/JSON column '' can't have a default value`. To avoid this I removed all default values from TEXT columns.

Tested and works on MySQL 5.7.
akalongman/php-telegram-bot,php-telegram-bot/core