Match argument names on the second line of definition

An error in the previous regular expression was preventing the first argument of successive lines of a definition from being matched unless they were at the very beginning of the line. Fixed by strictly matching the beginning of the argument.

Fixes #87 as first mentioned in github-linguist/linguist#2692.

Author: infininight

Syntaxes/Ruby.plist

@@ -418,7 +418,7 @@
 			<array>
 				<dict>
 					<key>begin</key>
-					<string>(?![\s,)])</string>
+					<string>(?=[&amp;*_a-zA-Z])</string>
 					<key>end</key>
 					<string>(?=[,)])</string>
 					<key>patterns</key>