added linux support

io/crossplatformlib.cpp

@@ -0,0 +1,25 @@
+#include "crossplatformlib.h"
+
+#include <QDebug>
+
+void *LibLoad(const QString &filename) {
+#ifdef _WIN32
+    LPCWSTR dll_fn_w = reinterpret_cast<const wchar_t*>(filename.utf16());
+    return LoadLibrary(dll_fn_w);
+#elif __linux__
+    return dlopen(filename.toUtf8(), RTLD_LAZY);
+#else
+    qWarning() << "Olive doesn't know how to open dynamic libraries on this platform, external libraries will not be functional";
+    return nullptr;
+#endif
+}
+
+QStringList LibFilter() {
+#ifdef _WIN32
+    return QStringList("*.dll");
+#elif __linux__
+    return QStringList("*.so");
+#elif __APPLE__
+    return QStringList("*.dylib");
+#endif
+}