Load OSD Manager in ctor not on plugin load.
Load OSD Manager in ctor not on plugin load.

Fixes issue CLIENT-69

Change-Id: I37bba19923b02e5d4390929aff08c82d1d6edbf7
Reviewed-on: http://gerrit.dmdirc.com/1541
Reviewed-by: Chris Smith <711c73f64afdce07b7e38039a96d2224209e9a6c@dmdirc.com>
Automatic-Compile: Greg Holmes <79e2475f81a6317276bf7cbb3958b20d289b78df@dmdirc.com>

csmith/DMDirc-Plugins,DMDirc/Plugins,DMDirc/Plugins,csmith/DMDirc-Plugins,DMDirc/Plugins,csmith/DMDirc-Plugins,csmith/DMDirc-Plugins,DMDirc/Plugins,csmith/DMDirc-Plugins,DMDirc/Plugins