qdoc: Fixed pure doc parser

qdoc: Fixed pure doc parser

This parser was meant to parse any file for
qdoc comments only, ignoring everything else
that is not inside a qdoc comment. But it
wasn't doing that. It was parsing all code,
regardless of the language, using the C++
parser. Now it has been corrected to look
at qdoc comments and skip over everything
else.

Note thast this means qdoc will expect a
qdoc topic command in each and every qdoc
comment in the file. The posiution of the
qdoc comment with respect to the code it is
meant to document is not taken into account
in the pure doc parser. This is in contrast
to the QML and C++ parsers which do take
comment location into account in some cases.

Change-Id: I0804a4149baa942b463e0b6990c71e4039ac1a50
Reviewed-by: Keith Isdale <keith.isdale@nokia.com>
Reviewed-by: Martin Smith <martin.smith@nokia.com>