SSH: Remove questionable warning in connection manager.

If there are still open channels in a connection being released,
that is not necessarily a mistake: The channels could already be
in the closing state, and it would be unreasonable for us to expect
API clients to always wait for confirmation before releasing the
connection, as this can complicate code quite a bit, turning a
synchronous operation into an asynchronous one.

Change-Id: If8c604c9ee1294728e7947c8d5c8130d6e704b49
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Custom Error Parser

Allow setting the following items from outside:
* capture regular expression,
* file name, line number and message capture position and
* whether to parse stdout, stderr or both

The parser functions can be unit-tested by running (Debug build of Qt
Creator needed):

qtcreator -test ProjectExplorer,testCustomOutputParsers

The data is passed to the custom parser in
CustomToolChain::outputParser().

The parser information is stored in toolchains.xml together with the
custom toolchain. A configuration widget is provided to set up and test
the regular expression against a sample error message.

Change-Id: I6191df3c44432943e0aeb16c48d8e79d35845d2e
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>