Remove unsupported `shader.um`

window::freezeCursor will always hide the cursor for some reason

Checking GamepadButton._count will cause unpredictable behavior.

Naming main module after one of the builtin modules will give a confusing error

Tophat crashes on drawing an image stored in a local variable

Docs: `image.um` module docs are confusing

Tophat crashes as it doesn't destroy unused render target buffers

Inline code in the docs is rendered as black on a black background

Do not use `free` with string buffer returned by `umkaAsm`

The RGBA order is reversed when setting the icon on the web.