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/value.cpp

@@ -1,9 +1,26 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2019 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
 #include "value.h"
 
-NodeValueDatabase::NodeValueDatabase()
-{
-
-}
+OLIVE_NAMESPACE_ENTER
 
 NodeValueTable NodeValueDatabase::operator[](const QString &input_id) const
 {
@@ -52,10 +69,6 @@ const QVariant &NodeValue::data() const
   return data_;
 }
 
-NodeValueTable::NodeValueTable()
-{
-}
-
 QVariant NodeValueTable::Get(const NodeParam::DataType &type, const QString &tag) const
 {
   NodeValue v = GetWithMeta(type, tag);
@@ -180,3 +193,5 @@ int NodeValueTable::GetInternal(const NodeParam::DataType &type, const QString &
 
   return index;
 }
+
+OLIVE_NAMESPACE_EXIT