Enabled XML documentation

Turned XML documentation back on. This allows XML comments to be used by
IntelliSense to be displayed while coding. Don't know why this was
originally turned off, as it is on by default.
Enabled XML documentation (continued)

Enabled it for the C# sub-projects as well. It is only generated in the
Debug builds, so is of no consequence for the development builds.
Method comments added

EmberAPI\clsAPICommon.vb - only partially completed
Merge remote-tracking branch 'upstream/master' into Code-Documentation
EmberAPI\clsAPICommon documented

Added baseline documentation to clsAPICommon. Also added more
descriptive error messages for the log, which should go a ways to help
debug issues.
EmberAPI\clsAPIDatabase documented

Added extensive method documentation. Also added fair amount of
parameter type checking to increase robustness and error tracking
capabilities.
Merge pull request #37 from Dekker500/Code-Documentation

Code documentation