Add support for recording/running ref tests

Ref tests use a recording of the terminal protocol and a serialization
of the grid state to check that the parsing and action handling systems
produce the correct result. Ref tests may be recorded by running
alacritty with `--ref-test` and closing the terminal by using the window
"X" button. At that point, the recording is fully written to disk, and a
serialization of important state is recorded. Those files should be
moved to an appropriate folder in the `tests/ref/` tree, and the
`ref_test!` macro invocation should be updated accordingly.

A couple of changes were necessary to make this work:

* Ref tests shouldn't create a pty; the pty was refactored out of the
  `Term` type.
* Repeatable lines/cols were needed; on startup, the terminal is resized
* by default to 80x24 though that may be changed by passing
  `--dimensions w h`.
* Calculating window size based on desired rows/columns and font metrics
  required making load_font callable multiple times.
* Refactor types into library crate so they may be imported in an
  integration test.
* A whole bunch of types needed symmetric serialization and
  deserialization. Mostly this was just adding derives, but the custom
  deserialization of Rgb had to change to a deserialize_with function.

This initially adds one ref test as a sanity check, and more will be
added in subsequent commits. This initial ref tests just starts the
terminal and runs `ll`.

tests/ref/ll/alacritty.recording

@@ -0,0 +1,27 @@
+%                                                                               
 

jwilm@kurast.local ➜  ~/code/alacritty  [?1h=[?2004hlll[?1l>[?2004l
+total 16440
+drwxr-xr-x   3 jwilm  staff   102B Nov  2 10:54 Alacritty.app
+-rw-r--r--   1 jwilm  staff    53K Nov 19 14:27 Cargo.lock
+-rw-r--r--   1 jwilm  staff   746B Nov 19 14:24 Cargo.toml
+-rw-r--r--   1 jwilm  staff    11K Jun 30 10:44 LICENSE-APACHE
+-rw-r--r--   1 jwilm  staff   1.6K Nov  2 10:52 Makefile
+-rw-r--r--   1 jwilm  staff    49B Jun  9 18:56 TASKS.md
+-rwxr-xr-x   1 jwilm  staff   1.7M Sep 26 10:49 alacritty-pre-eloop
+-rw-r--r--   1 jwilm  staff   255B Nov 19 14:31 alacritty.recording
+-rw-r--r--   1 jwilm  staff   6.5K Nov 17 17:18 alacritty.yml
+-rw-r--r--   1 jwilm  staff   1.1K Jun 30 10:44 build.rs
+drwxr-xr-x   6 jwilm  staff   204B Oct 10 10:46 copypasta
+drwxr-xr-x   3 jwilm  staff   102B Jun  9 18:56 docs
+-rwxr-xr-x   1 jwilm  staff   2.2M Nov 11 17:53 exitter
+drwxr-xr-x   5 jwilm  staff   170B Jun 28 14:50 font
+-rwxr-xr-x   1 jwilm  staff   2.2M Nov 14 13:27 hardcoded_bindings_alacritty
+drwxr-xr-x   6 jwilm  staff   204B Nov  2 10:54 macos
+drwxr-xr-x   4 jwilm  staff   136B Oct 27 17:59 res
+-rw-r--r--   1 jwilm  staff    19B Nov 11 16:55 rustc-version
+drwxr-xr-x   5 jwilm  staff   170B Oct 10 10:46 scripts
+drwxr-xr-x  17 jwilm  staff   578B Nov 19 14:30 src
+drwxr-xr-x   5 jwilm  staff   170B Jun 28 15:49 target
+-rw-r--r--   1 jwilm  staff   8.1K Nov 17 11:13 thing.log
+-rw-r--r--   1 jwilm  staff   3.5K Sep  1 11:27 tmux-client-23038.log
+-rwxr-xr-x   1 jwilm  staff   1.8M Sep 22 12:03 with_parallel
+%                                                                               
 

jwilm@kurast.local ➜  ~/code/alacritty  [?1h=[?2004h

tests/ref/ll/size.json

@@ -0,0 +1 @@
+{"width":1124.0,"height":628.0,"cell_width":14.0,"cell_height":26.0}