ui: precollapse files in code view

This change shows the files in the code view minimized, if more than 5. This greatly improves performance, because code
and annotations won't get loaded until needed. Files including declarations or definitions of the active symbol are
still expanded. The number of references in each file is now shown in it's title bar. Clicking the title bar allows for
expanding and collapsing as well now.

src/lib/data/location/TokenLocationFile.cpp

@@ -25,6 +25,24 @@ size_t TokenLocationFile::getTokenLocationLineCount() const
 	return m_lines.size();
 }
 
+size_t TokenLocationFile::getUnscopedStartTokenLocationCount() const
+{
+	size_t count = 0;
+	for (const TokenLocationLinePairType& line : m_lines)
+	{
+		line.second->forEachStartTokenLocation(
+			[&count](TokenLocation* location)
+			{
+				if (!location->isScopeTokenLocation())
+				{
+					count++;
+				}
+			}
+		);
+	}
+	return count;
+}
+
 const FilePath& TokenLocationFile::getFilePath() const
 {
 	return m_filePath;