aded buffer_getc, buffer_getn get n bytes less only if EOF and

buffer_get_token for getting n bytes till finding a termination char or
EOF/error.

buffer/buffer_getn.c

@@ -0,0 +1,13 @@
+#include "byte.h"
+#include "buffer.h"
+
+int buffer_getn(buffer* b,char* x,unsigned int len) {
+  int blen;
+
+  for(blen=0;blen<len;++blen) {
+    if ((r=buffer_getc(b,x))<0) return r;
+    if (r==0) return blen;
+    ++x;
+  }
+  return blen;
+}