This updates CPPCheckTool to subclass the newer BaseTool, and to

use the newer features it offers (dependencies, improved configurable

file extension handling, centralized base command building, and

standardized column/severity/error code output).
The new version of the tool has safer error report parsing. The old

version used manual string parsing, and had the potential to get

confused. The new version uses a regex to better match lines.
There are a couple changes in behavior:
1) Comments on non-errors (those marked as style, performance, etc.) no

   longer have issues turned off. We just use the default for the tool,

   no matter what.
2) "Category" has been renamed to "Severity" and "Sub Category" to

   "Error code" in the output.
Unit tests were added to cover the new parsing, and to provide

integration tests.

All unit tests pass on Python 2.7 and 3.x.