Drop guilegh interface

All of guile's interface files now use the scm interface.
This should not affect any users. Swig generated code
using the scm interface can be mixed with gh interface
using user code.
It does simplify maintenance of the guile swig code though.

Lib/cdata.i

@@ -17,7 +17,7 @@ typedef struct SWIGCDATA {
 
 #if SWIGGUILE
 %typemap(out) SWIGCDATA {
-   $result = gh_str2scm($1.data,$1.len);
+   $result = scm_mem2string($1.data,$1.len);
 }
 %typemap(in) (const void *indata, int inlen) = (char *STRING, int LENGTH);
 #elif SWIGCHICKEN