Add document views

The document views is used to handle multiple types of document as tab documents to be displayed in the main window.

Also make some modifications/improvements to the main window UI

Depends on !5 (merged)

src/UI/AudioVisualizer.cc

@@ -29,8 +29,8 @@ AudioVisualizer::AudioVisualizer(AudioContext::StreamPtr stream, QWidget *parent
         stream->decodeData();
     }
 
-    double *data = stream->getDecodedData();
-    if (data == nullptr)
+    double *decodedData = stream->getDecodedData();
+    if (decodedData == nullptr)
         throw std::logic_error("the passed stream is not decoded");
 
     const size_t size     = stream->getDecodedDataSize();
@@ -56,7 +56,7 @@ AudioVisualizer::AudioVisualizer(AudioContext::StreamPtr stream, QWidget *parent
 
     for (size_t x = 0, i = 0; i < size - height; i += decalage, ++x) {
         parallel_for (size_t j = 0; j < height; j++) {
-            const double curr_dat = data[i + j];
+            const double curr_dat = decodedData[i + j];
             const double window_modifier =
                 (1 - cos(2 * M_PI * static_cast<double>(j) / static_cast<double>(height - 1))) / 2;
             float value = static_cast<float>(window_modifier * curr_dat);