src/libvlc.c,include/vlc/vlc.h, include/variables.h: added a new a API to libvlc called VLC_VariableType, this API allows to retrieve the type of a VLC variable. this API is very useful for binding with highlevel languages, such as javascript, VBScript, etc... which allow for weakly typed variables such as Javascript. in order to support the VLC_VariableType API, i've had to move the variable type definitions from variables.h to vlc/vlc.h

vlccontrol.cpp, axvlc.idl, axvlc.tlb, axvlc_idl.h: added a getVariable and setVariable to provide support for VLC_GetVariable and VLC_SetVariable respectively,and requires the new VLC_VariableType API.

main.cpp, viewobject.h, viewobject.cpp: support for advise on viewobject