remove special case stralloc textcode functions

write generic stralloc and array textcode wrapper functions
change textcode API to use long instead of int
add cescape fmt and scan functions to textcode
add fmt_foldwhitespace to textcode

textcode/scan_base64.c

@@ -12,7 +12,7 @@ static inline int dec(unsigned char x) {
   }
 }
 
-unsigned int scan_base64(const char *src,char *dest,unsigned int *destlen) {
+unsigned long scan_base64(const char *src,char *dest,unsigned long *destlen) {
   unsigned short tmp=0,bits=0;
   register const unsigned char* s=(const unsigned char*) src;
   const char* orig=dest;