Table map and error event improvements

[jmealo]

Improvements:

1. ctrlConnection errors and unhandledErrors will be relayed by Zongji
2. The table map now includes constraints (null or object) and nullable (boolean) properties.

For discussion

1. I'd like to store the type rather than the code. Will this break anything internally?

Given the following DDL:

CREATE TABLE `example_table` (
  `ID` int(11) DEFAULT NULL,
  `student_id` int(11) NOT NULL DEFAULT '0',
  `section_id` int(11) NOT NULL DEFAULT '0',
  `teacher_id` int(11) NOT NULL DEFAULT '0',
  `resource_id` int(11) NOT NULL DEFAULT '0',
  `comment` text,
  `rating` tinyint(4) DEFAULT NULL,
  PRIMARY KEY (`section_id`,`student_id`,`resource_id`,`teacher_id`),
  UNIQUE KEY `ID` (`ID`)
);

Your table map columns would look like this:

[
  {
    "name": "ID",
    "charset": null,
    "type": 3,
    "nullable": true,
    "constraint": {
      "type": "UNIQUE",
      "position": 1,
      "name": "ID"
    }
  },
  {
    "name": "student_id",
    "charset": null,
    "type": 3,
    "nullable": false,
    "constraint": {
      "type": "PRIMARY KEY",
      "position": 2,
      "name": "PRIMARY"
    }
  },
  {
    "name": "section_id",
    "charset": null,
    "type": 3,
    "nullable": false,
    "constraint": {
      "type": "PRIMARY KEY",
      "position": 1,
      "name": "PRIMARY"
    }
  },
  {
    "name": "teacher_id",
    "charset": null,
    "type": 3,
    "nullable": false,
    "constraint": {
      "type": "PRIMARY KEY",
      "position": 4,
      "name": "PRIMARY"
    }
  },
  {
    "name": "resource_id",
    "charset": null,
    "type": 3,
    "nullable": false,
    "constraint": {
      "type": "PRIMARY KEY",
      "position": 3,
      "name": "PRIMARY"
    }
  },
  {
    "name": "comment",
    "charset": "utf8",
    "type": 252,
    "nullable": true,
    "metadata": {
      "length_size": 2
    }
  },
  {
    "name": "rating",
    "charset": null,
    "type": 1,
    "nullable": true
  }
]         

[jmealo]

This is how a DBA taught me to format SQL for readability, it's opinionated so I'm fine with just truncating it at 80 characters onto however many lines if that makes everyone happy.

It seemed like a good idea to get rid of the extra spaces once rather than sending them over with every query. If the join bothers anyone it can be converted to a string, it's only going to run once so performance shouldn't be a concern.