* devdraw: cocoa metal screen uses a dirty hack to make everything smooth * devdraw: cocoa metal screen uses a layer to make fullscreen applications behave * devdraw: macOS cocoa metal fix resizeimg without img * devdraw: macOS cocoa metal uses blit instead of render We directly use the blit command encoder to copy texture to the framebuffer. We no longer need to compile the metal shader every time the application starts just for rendering a flat 2D surface. * travis: add osx images covering 10.13 and 10.14

The commit that introduced this was pushed accidentally. It is not a good idea to do this. (It breaks programs that think that a clean window means the body matches the on-disk file.)

Some libraries that depend on devdraw don't know about 32x32 cursor -- mainly 9fans.net/go/draw.

It is possible to receive multiple screen resize events, and resizeimg would be called for different sizes, before _flushmemscreen actually gets called with rectangle sizes different from the most recent resizeimg call. The size mismatch would trigger illegal memory access inside _flushmemscreen. This commit protects _flushmemscreen by returning early if the requested rectangle is outside of the current texture rectangle.

Fixes bug where devdraw does not "notice" mouse position after task switch. Fixes https://github.com/9fans/plan9port/issues/232.

Fixes #235.

Auto-indent mode leaves trailing spaces on blank lines as you type past them, so silently elide them from the window content as it gets written back to disk. Another option would be to remove them from the window entirely during Put, but they're actually nice to have while editing, and to date Put has never modified the window content.