various: encapsulate all code in the olive namespace to avoid name collisions

Large-scale code cleanup. Also adds a license to the top of all files that were
missing it.

app/panel/tool/tool.cpp

@@ -23,6 +23,8 @@
 #include "core.h"
 #include "widget/toolbar/toolbar.h"
 
+OLIVE_NAMESPACE_ENTER
+
 ToolPanel::ToolPanel(QWidget *parent) :
   PanelWidget(parent)
 {
@@ -51,3 +53,5 @@ void ToolPanel::Retranslate()
 {
   SetTitle(tr("Tools"));
 }
+
+OLIVE_NAMESPACE_EXIT