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/.gitignore b/.gitignore
index 4e4f1c5..554879a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -35,6 +35,7 @@
 tests/alloc/AllocTest
 tests/rlcmac/RLCMACTest
 tests/tbf/TbfTest
+tests/types/TypesTest
 tests/emu/pcu_emu
 tests/testsuite
 tests/testsuite.log