improve channel mentions (#146)

something like @; was crashing the app.
this should be better.

ui/util/remark-lbry.js

@@ -7,9 +7,9 @@ export const punctuationMarks = [',', '.', '!', '?', ':', ';', '-', ']', ')', '}
 
 const mentionToken = '@';
 // const mentionTokenCode = 64; // @
-const mentionRegex = /@[^\s()"]*/gm;
 
 const invalidRegex = /[-_.+=?!@#$%^&*:;,{}<>\w/\\]/;
+const mentionRegex = /@[^\s()"-_.+=?!@$%^&*;,{}<>/\\]*/gm;
 
 function handlePunctuation(value) {
   const protocolIndex = value.indexOf('lbry://') === 0 ? protocol.length - 1 : 0;