This adds a DirectWrite font rasterizer for Windows and enables
subpixel rendering and hinting.

It also completely replaces rusttype for font rendering on Windows,
allowing Alacritty to use the native font stacks on all operating systems.

Fixes #1673.
Fixes #2316.

This fixes a recent regression in
cfc20d4f34dca535654cc32df18e785296af4cc5 which broke cursor colors when
specified in the `colors.cursor` field in the config.

It also removes a lot of unneeded code from the font crate related to
the cursor rendering.

This fixes #2338.

If a resize event is identical to the current size, it is no longer
propagated but the resize is discarded immediately.

To further prevent resizes when not necessary, the list of monitors is
enumerated and the DPR of the first display is assumed to be the target
DPR.

This allows spawning a window with dimensions when the config has
columns and lines specified and the window only needs to be resized if
the estimated DPR is not correct.

Fixes #1825.
Fixes #204.

The rusttype backend did not properly support manually specifying font
styles, but instead chose to panic when they are specified.

The rusttype implementation now provides a proper implementation for
handling `bold`, `italic` and `regular` font styles.

This fixes #2020.

The general style for errors, warnings and info messages is to start
with a capitalized letter and end without a period. The main exception
is when dealing with nouns that are clearer with special case handling,
e.g. "macOS failed to work" or "ioctl is borked".

Since bitmap fonts do not provide their own underline metrics, the
self-calculated metrics which have been used for rusttype are now also
used for bitmap fonts with freetype.

The rusttype and bitmap fallback metrics have incorrectly offset the
underline by the underline height. Since the position is already defined
as the center point, that is not necessary.

All rounding and clamping has also been removed from the font library,
so that the raw values are reported now. The clamping and rounding is
now done in the line renderer.

This makes use of the new rectangle rendering methods used to display
the colored visual bell to add proper underline and strikeout support to
Alacritty.

This resolves a lot of NLL issues, however full NLL will be necessary to
handle a couple of remaining issues.