PluginManager: don't use `pluginInitializer_*()` for static plugins.

This function name will be used for slightly different purpose.
PluginManager: don't keep any state between test cases.

Depending on fuckups in previous test case is way to hell.
PluginManager: renamed PluginTest to Test.

It tests everything, not just Plugin class.
PluginManager: store StaticPluginObject via pointer.

The object will be used elsewhere later.
PluginManager: don't recreate Resource instance every time.
PluginManager: no need to have [Static]PluginObject, just [Static]Plugin.

As we now have AbstractPlugin, the internal names don't conflict with
anything anymore.
PluginManager: accessing additional info about static plugins via union.

A little bit ugly code, but it looks cleaner than having info about both
static and dynamic plugin in Plugin itself with each plugin using only
half of the data.
PluginManager: rename variable to be consistent.
PluginManager: support for plugin initialization and finalization.

You can now "override" AbstractPlugin::initialize() and
AbstractPlugin::finalize() and implement initialization/finalization
routines there.
PluginManager: increase plugin API version to 3.

A lot of incompatible changes lately.
PluginManager: improve initialize()/finalize() documentation.
PluginManager: described two bugs.

Will fix them later (hopefully).
Allow building Corrade as static library.

Everything works and test pass except for Utility::Resource, which has
probably some problems with (uninitialized or dropped) static member.
Utility: fix Resource with static build.
Option to build static libraries with position-independent code.
FindCorrade.cmake: added 'dl' to CORRADE_PLUGINMANAGER_LIBRARIES.

At least static build needs this.
Merge branch 'master' into compatibility

Conflicts:
	CMakeLists.txt
	src/PluginManager/AbstractPluginManager.cpp
	src/PluginManager/Test/Dog.h
GCC 4.6 compatibility: cannot initialize via new and initializer list.

Probably a bug which is fixed in 4.7.
Merge branch 'master' into compatibility
GCC 4.5 compatibility: no range-based for.