getting rgb of a Color and fixes set_viewport arguments
replace a to _ to avoid warning
Merge pull request #204 from bbodi/some_fixes

getting r, g and b components of a Color and fixes set_viewport arguments
rwops: Remove `Collection` impl

The `Collection` trait was removed as part of the
collections reform in Rust master.

Instead, we impl it for `RWops` directly.
Merge pull request #207 from crumblingstatue/master

rwops: Remove `Collection` impl
Refer to enum variants with their full name (see rust-lang/rust#18973).
Remove "Axis" suffix from ControllerAxis enum variants.
Remove "Button" suffix from ControllerButton enum variants.
Remove "EventType" suffix from EventType enum variants.
Remove "WindowEventId" suffix from WindowEventId enum variants.
Remove "Event" suffix from Event enum variants.
Remove "Key" suffix from KeyCode enum variants.
Remove "Cursor" suffix from SystemCursor enum variants.
Remove "Mouse" suffix from Mouse enum variants.
Remove "Driver" prefix from RenderDriverIndex enum variants.
Remove "Access" prefix from TextureAccess enum variants.
Remove "Blend" prefix from BlendMode enum variants.
Remove "Flip" prefix from RendererFlip enum variants.
Remove "Parent" suffix from RendererParent enum variants.
Remove "ScanCode" suffix from ScanCode enum variants.