Don't attempt to draw without a valid VAO

This is a temporary fix. The real solution is to not create drawing
RenderCommands until all the necessary information is available.

Change-Id: I4cbe15947d356cd14a7e90eec050dd85990728c9
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Fix initialization order

Change-Id: I4e10cf4412dec40e18f50066956233ef8b024e66
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Fix glsl errors in simple-qml

Change-Id: Id4fdc23716aaecc84471577c35573897c3e6b890
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Texture subclass of QNode

Change-Id: I0b6f3a6e4dfa75ce1cc29ee38bb709b8bad6a88f
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Texture renamed to QTexture

Change-Id: I6f5570ce042b8d3ef44aa76c1fd8ce3a1dde4d3c
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Added QRenderAttachment

Will be used by QRenderTarget to specify a list of attachments to use with the
FBO.

Change-Id: I9b2c5383884e5d21df2646edc2a00337a45dcf69
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Added QRenderTarget

Change-Id: Id1e84ae8f23ddba1d2c97519b8762af801b03a38
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Avoid downcasting from double to float

Change-Id: I02fab517a44f3071e0530f1a6dab42b75b0f2814
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>