Improve on cider-repl--root-ns-highlight-template regexp

 - Disallow highlight spilling over () as in ns.foo.bar(file.clj:123)).

 - Start matching at the beginning of the symbol, not word. Particularly inhibit
   matching of namespaced keywords (which could be many).

Author: vspinu

cider-repl.el

@@ -561,7 +561,7 @@ When there is a possible unfinished ansi control sequence,
                    (buffer-local-value 'cider-repl--ns-forms-plist connection)
                    ns)))))
 
-(defvar cider-repl--root-ns-highlight-template "\\<\\(%s\\)[^$/: \t\n]+"
+(defvar cider-repl--root-ns-highlight-template "\\_<\\(%s\\)[^$/: \t\n()]+"
   "Regexp used to highlight root ns in REPL buffers.")
 
 (defvar-local cider-repl--root-ns-regexp nil