liq| ui| menu|: "Load Renderer" --> "Choose Renderer"
liq|: use $g_ShowliqLog to control the liqlog() output again.
liq| automation|: load liquid/renderman/elvishray plugins before opening scenes. And remove mtor.mll dependence in some scenes.
liq| ui|:
1. global $renderer --> $g_liqRenderer
2. remove "Renderer" UI in liquidGlobals.mel
3. "pluginInfo -q -loaded -name XXX"  -->  isRendererLoaded(XXX)
4. +isCurrentRenderer($rnd)
liq| mel|: isCurrentRenderer(), return false if liquidGlobals not exists.
liq|: 1.create liquidGlobals when liquid plug-in loaded.
2.run liquidUpdateRenderer() after switch the renderer.
3.liquidCreateGlobals()->liquidLoadGlobals2()->load maya2renderer_3delgiht.lg
liq| er|: set camera.visibility to 1, and restore the value after rendering.
liq| er| check|: check fabs(transform.scale)!=0 to avoid the degenerated mesh. Not show the mel command.