First pass at support for multiple datasets.
Not working yet:
-  CHART, FILTER, ROLLUP headers
-  vertical parameter in OPTIONS header
-  AdoDB support (works as is, but no way to have multiple datasets)
-  default_dataset parameter for OPTIONS header
-  ability to choose which dataset(s) are used in CSV, JSON, and XML report formats
-  selectable parameter in OPTIONS header

For issue #102
Fixing Rollup header to work with multiple datasets.
Split OPTIONS header into OPTIONS and FORMATTING. OPTIONS header contains report-wide settings and FORMATTING header contains dataset specific settings.
OPTIONS remains backwards compatible and any formatting parameters will apply to all datasets.
Made vertical, limit formatting options work with multiple datasets.

For issue #102
Fix selectable reports with multiple datasets.
Fix FILTER and COLUMNS headers to work with multiple datasets.
Fix chart header to work with multiple datasets.
Add Multi-dataset version of JSON and XML report formats.
Add ability to specify which dataset(s) are used in CSV, JSON, and XML formats.
Add ability to add titles to datasets in MySQL reports.
New preferred MySQL comment syntax is "-- @dataset true" instead of "-- @dataset = true".  This better matches javadoc and phpdoc standards.
Merge pull request #103 from jdorn/multiple_report_tables

Support Multiple Datasets in a Single Report