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/codec/ffmpeg/ffmpegencoder.cpp

@@ -1,3 +1,23 @@
+/***
+
+  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 "ffmpegencoder.h"
 
 #include <QFile>
@@ -5,6 +25,8 @@
 #include "ffmpegcommon.h"
 #include "render/pixelformat.h"
 
+OLIVE_NAMESPACE_ENTER
+
 FFmpegEncoder::FFmpegEncoder(const EncodingParams &params) :
   Encoder(params),
   fmt_ctx_(nullptr),
@@ -17,7 +39,7 @@ FFmpegEncoder::FFmpegEncoder(const EncodingParams &params) :
 {
 }
 
-void FFmpegEncoder::WriteAudio(const AudioRenderingParams &pcm_info, const QString &pcm_filename, const TimeRange& range)
+void FFmpegEncoder::WriteAudio(AudioRenderingParams pcm_info, const QString &pcm_filename, TimeRange range)
 {
   QFile pcm(pcm_filename);
   if (pcm.open(QFile::ReadOnly)) {
@@ -504,3 +526,5 @@ void FFmpegEncoder::Error(const QString &s)
 
   Close();
 }
+
+OLIVE_NAMESPACE_EXIT