c++/class: Use yas-c++-class-name

This does the same yas/substr calls previously done by the snippet.

Author: mineo

snippets/c++-mode/class

@@ -5,7 +5,7 @@
 class ${1:Name}
 {
 public:
-    ${1:$(yas/substr yas-text "[^: ]*")}();
-    ${2:virtual ~${1:$(yas/substr yas-text "[^: ]*")}();}
+    ${1:$(yas-c++-class-name yas-text)}();
+    ${2:virtual ~${1:$(yas-c++-class-name yas-text)}();}
 };
 $0