Make asset compression optional at compile time (#1825)

This will be needed to later support zero-copy deserialization of independent
syntax sets, but is interesting and useful on its own.

Instead of deferring serialization and deserialization to syntect, we implement it
ourselves in the same way, but make compression optional.

Cargo.toml

@@ -45,7 +45,9 @@ regex-fancy = ["syntect/regex-fancy"] # Use the rust-only "fancy-regex" engine
 atty = { version = "0.2.14", optional = true }
 ansi_term = "^0.12.1"
 ansi_colours = "^1.0"
+bincode = "1.0"
 console = "0.14.1"
+flate2 = "1.0"
 lazy_static = { version = "1.4", optional = true }
 lazycell = "1.0"
 thiserror = "1.0"
@@ -72,7 +74,7 @@ default-features = false
 [dependencies.syntect]
 version = "4.6.0"
 default-features = false
-features = ["parsing", "dump-load"]
+features = ["parsing"]
 
 [dependencies.clap]
 version = "2.33"