Grammar: Replace \w to allow _ in regex replace

This allows using `_` as a delimiter as such:

```perl
$asd =~ s_a_v_g;
```

Syntaxes/Perl.plist

@@ -635,7 +635,7 @@
 		</dict>
 		<dict>
 			<key>begin</key>
-			<string>\b(?=s([^\s\w\[({&lt;]).*\1([egimosxradlupc]*)([\}\)\;\,]|\s+))</string>
+			<string>\b(?=s([^\sa-zA-Z0-9\[({&lt;]).*\1([egimosxradlupc]*)([\}\)\;\,]|\s+))</string>
 			<key>comment</key>
 			<string>string.regexp.replaceXXX</string>
 			<key>end</key>
@@ -662,7 +662,7 @@
 			<array>
 				<dict>
 					<key>begin</key>
-					<string>(s\s*)([^\s\w\[({&lt;])</string>
+					<string>(s\s*)([^\sa-zA-Z0-9\[({&lt;])</string>
 					<key>captures</key>
 					<dict>
 						<key>0</key>
@@ -715,7 +715,7 @@
 				</dict>
 				<dict>
 					<key>begin</key>
-					<string>([^\s\w\[({&lt;])</string>
+					<string>([^\sa-zA-Z0-9\[({&lt;])</string>
 					<key>captures</key>
 					<dict>
 						<key>0</key>