[Clam-devel] today's commits

[Pau Arumi]

 * commited patch from Andreas Calvo: DummyLadspa loads a hardcoded 
plugin. Work in progrss
 * Network::AddProcessing removed nasty comment
 * moved AudioSource from Processing/Controls/ to Processing/
 * cleaned/commented out some qt-related checks in libs/SConstruct
 * added new PullFlowControl.*xx now is a naive flow control
 * TestsCallbackBasedNetwork: new test with a filter working
 * INSTALL: added build-essential