Trivial changes: whitespace and modes. Remote whitespace at the ends of lines. Remove blank lines from the ends of files. Change modes on source files so that they are not executable. Signed-off-by: Dan Cross <cross@gajendra.net>

devdraw: add Cursor2 support on macOS 10.14 Mojave This replaces the pixel-art scaling algorithm used for upscaling before. The results were not crisp enough to serve as everyday cursors.

devdraw: rewrite the Cocoa screen using Metal Add a new macOS cocoa screen, cocoa-screen-metal.m. Rewrite the macOS cocoa drawing code to use the builtin runloop, and use Metal to push pixels with CAMetalLayer. Remove all of the deprecated code, and simplify some of the logic. Modify mkwsysrules.sh such that the new code is used only when the system version is equal or higher than 10.14. Allow touch events to simulate mouse clicks: three finger tap for the middle mouse button; four finger tap for the 2-1 chord. Support Tresize. Scale 16x16 Cursor up to 32x32 with an EPX algorithm. Support macOS input sources including the basic dead keys and the advanced CJK input methods. Increase the communication buffers in cocoa-srv.c to allow more input, especially for long sentences prepared by the macOS input souces.

Cocoa Devdraw: cursor fix R=rsc CC=plan9port.codebot http://codereview.appspot.com/5356050