Merge pull request #154 from sunyc/master

Changes for alpha7.4
Merge pull request #155 from sunyc/master

use std::max, std::min instead of macro, fix compile warning.
Merge pull request #156 from sunyc/master

Switch tick_event priority_queue to multimap.
Merge pull request #157 from sunyc/master

Correctly push/pop error context for user events.
Merge pull request #159 from sunyc/master

Changes for alpha7.4
Define for MYSQL Fetch NewDecimal Type
This is needed in my system for read a column SUM(xxx) in a SELECT.
Merge pull request #160 from zoilder/MYSQL_Fetch_NewDecimal_Type

PACAKGE_DB:  FIELD_TYPE_NEWDECIMAL for MYSQL
Merge pull request #163 from sunyc/master

More Changes for alpha7.4
Increase default evaluator stack to 6000.