Define a highlighting file for Clojure

This isn't provided upstream, and the parse tree doesn't have a lot of
information, but we can at least handle string literals and keywords.

CHANGELOG.md

@@ -12,6 +12,8 @@ would be excluded from context.
 Fixed an issue where lines containing only whitespace would be
 highlighted in purple.
 
+Improved Clojure syntax highlighting.
+
 ### Parsing
 
 Added support for Dart.

sample_files/clojure_after.clj

@@ -2,6 +2,7 @@
 
 (defn example
   [x]
+  "Does stuff."
   (-> {:more (inc x)
        :less (dec x)}
       (assoc :twice (+ x x))))

sample_files/clojure_before.clj

@@ -2,6 +2,7 @@
 
 (defn example
   [x]
+  "Does stuff."
   (println "hello!")
   {:more (inc x)
    :less (dec x)})

sample_files/compare.expected

@@ -5,7 +5,7 @@ sample_files/change_outer_before.el sample_files/change_outer_after.el
 1e144818ad54091b05e58e2c617add8f  -
 
 sample_files/clojure_before.clj sample_files/clojure_after.clj
-8316bcd959ce706ac07011f6dc31c93a  -
+792e31e6c057b10d4a2e27932c20c33b  -
 
 sample_files/comments_before.rs sample_files/comments_after.rs
 d899ce2b86f03851fa02823a1ff9aa3f  -

src/tree_sitter_parser.rs

@@ -144,7 +144,11 @@ pub fn from_language(language: guess::Language) -> TreeSitterConfig {
                 delimiter_tokens: (vec![("{", "}"), ("(", ")"), ("[", "]")])
                     .into_iter()
                     .collect(),
-                highlight_query: ts::Query::new(language, "").unwrap(),
+                highlight_query: ts::Query::new(
+                    language,
+                    include_str!("../vendor/highlights/clojure.scm"),
+                )
+                .unwrap(),
             }
         }
         CommonLisp => {

vendor/highlights/clojure.scm

@@ -0,0 +1,7 @@
+;; Basic, limited highlighting for Clojure.
+;; TODO: submit upstream.
+
+(comment) @comment
+(str_lit) @string
+
+(kwd_lit) @constant