CL 0.8 Canvas patch, get-rid-of-warnings patch

[Trigve]

Hi,
I send 2 patches, first for getting out warnings (need auditing?)... 2. fixed bug, when destroying canvas, cnavas isn't detached from surface, so when surface is used, it is pointing to nonexistent canvas

Trigve

[Trigve]

Here is another patch, that fixed bug, when using sprite cursor. If then CL_Window.hide_cursor() is called, cursor doesn't hide. Plus some warnings removal

[Seth]

Awesome, thanks Trigve. Applied.