Add slime syntax, closes #252

compiler/fish.vim

@@ -0,0 +1,11 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'fish') == -1
+  
+if exists('current_compiler')
+    finish
+endif
+let current_compiler = 'fish'
+
+CompilerSet makeprg=fish\ --no-execute\ %
+execute 'CompilerSet errorformat='.escape(fish#errorformat(), ' ')
+
+endif