Added API method for (re)setting texture search paths.

Was only possible on startup before, changing the paths required recreating the whole projectM instance. Now, the method will only reset the texture manager, but not the shaders and presets.

src/libprojectM/ProjectM.cpp

@@ -108,6 +108,12 @@ auto ProjectM::InitRenderToTexture() -> unsigned
     return m_renderer->initRenderToTexture();
 }
 
+void ProjectM::SetTexturePaths(std::vector<std::string> texturePaths)
+{
+    m_textureSearchPaths = std::move(texturePaths);
+    m_renderer->SetTextureSearchPaths(m_textureSearchPaths);
+}
+
 void ProjectM::ResetTextures()
 {
     m_renderer->ResetTextures();