add buffer_putsa, buffer_get_token_sa, buffer_getline_sa, stralloc_chomp

and stralloc_chop

buffer/buffer_getline_sa.c

@@ -0,0 +1,6 @@
+#include "stralloc.h"
+#include "buffer.h"
+
+int buffer_getline_sa(buffer* b,stralloc* sa) {
+  return buffer_get_token_sa(b,sa,"\n",1);
+}