FindMagnum: it's FindFreetype.cmake, not FindFreeType.cmake.

Although the library is still named FreeType. Fixes warnings in
dependent projects.
AbstractFramebuffer::BlitMask is available also in ES.

Probably got forgotten when adding ES extensions support.
Doc++
Math: disable denormalize() test for UnsignedLong.

It works with GCC and -O3, but fails on unoptimized code.
Don't spit assert in Mesh::addVertexBuffer() when it's not needed.

Vertex count is needed only for more than one attribute. Also updated
the assertion message to include function name.
Better assertion message on ResourceManager destruction.
DebugTools: added ForceRenderer.

Visualizes force using arrow.
Disable optimization in development PKGBUILD.

Saves a lot of compilation time (5:50 before, 3:40 now).