SL-6109 Implement keybindings

indra/llcommon/CMakeLists.txt

indra/llcommon/indra_constants.h

indra/llcommon/llkeybind.cpp

indra/llcommon/llkeybind.h

indra/llwindow/llmousehandler.cpp

indra/llwindow/llmousehandler.h

indra/llxml/CMakeLists.txt

indra/llxml/llcontrol.h

indra/newview/llfloaterpreference.cpp

indra/newview/llfloaterpreference.h

indra/newview/lltool.cpp

indra/newview/lltool.h

indra/newview/lltoolpie.cpp

indra/newview/lltoolpie.h

indra/newview/llviewerwindow.cpp

indra/newview/llviewerwindow.h

indra/newview/llvoiceclient.cpp

indra/newview/llvoiceclient.h