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/node/block/gap/gap.cpp

@@ -20,6 +20,8 @@
 
 #include "gap.h"
 
+OLIVE_NAMESPACE_ENTER
+
 GapBlock::GapBlock()
 {
 }
@@ -48,3 +50,5 @@ QString GapBlock::Description() const
 {
   return tr("A time-based node that represents an empty space.");
 }
+
+OLIVE_NAMESPACE_EXIT

app/node/block/gap/gap.h

@@ -23,6 +23,8 @@
 
 #include "node/block/block.h"
 
+OLIVE_NAMESPACE_ENTER
+
 /**
  * @brief Node that represents nothing in its respective track for a certain period of time
  */
@@ -44,4 +46,6 @@ private:
 
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // TIMELINEBLOCK_H