[qt] Rename QMapboxGL to QMapLibreGL (#338)

* Rename QMapboxGL to QMapLibreGL

* Add missing QDebug includes

* Fix Qt CMake config

* Fix geojson warning

* Remove redundant OpenGL dependency

* Put everything under QMapLibreGL namespace

* Reorganise headers

Co-authored-by: Rinigus <rinigus.git@gmail.com>

platform/qt/src/mbgl/string_stdlib.cpp

@@ -0,0 +1,24 @@
+#include <mbgl/util/platform.hpp>
+
+#include <QByteArray>
+#include <QString>
+
+#include <string>
+
+namespace mbgl {
+namespace platform {
+
+std::string uppercase(const std::string& str) {
+    auto upper = QString::fromUtf8(str.data(), static_cast<int>(str.length())).toUpper().toUtf8();
+
+    return std::string(upper.constData(), upper.size());
+}
+
+std::string lowercase(const std::string& str) {
+    auto lower = QString::fromUtf8(str.data(), static_cast<int>(str.length())).toLower().toUtf8();
+
+    return std::string(lower.constData(), lower.size());
+}
+
+} // namespace platform
+} // namespace mbgl