types: Add a simple testcase for basic types and fix the LLC code

* Make append_data, remaining_space and fits_in_current.. work
  on m_length and not the index. This ways things can't overflow.
* The current API consumer was moving the m_index so it should have
  worked okay.
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 4d77005..27f66b9 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -22,3 +22,10 @@
 cat $abs_srcdir/tbf/TbfTest.err > experr
 AT_CHECK([$abs_top_builddir/tests/tbf/TbfTest], [0], [expout], [experr])
 AT_CLEANUP
+
+AT_SETUP([types])
+AT_KEYWORDS([types])
+cat $abs_srcdir/types/TypesTest.ok > expout
+cat $abs_srcdir/types/TypesTest.err > experr
+AT_CHECK([$abs_top_builddir/tests/types/TypesTest], [0], [expout], [experr])
+AT_CLEANUP