We are only checking against GL_MAX_TEXTURES when binding samplers,
when we should be checking against the maximum number of samplers that
the card supports.  Spotted by H. Verbeet.

- forward MLGetUILanguage to kernel32
- correct type of parameter to MLLoadLibrary

result in premature termination of the send.

When several debug formats (eg stabs & dwarf2) exist in the same
module, allow to load them all (this is needed when different
compilation units are compiled with different debug options).

Walking the whole lot, not doing anything interesting apart from
traversing the data.

- split the data structures for walking through the data (abbrev,
  cu... -> traverse_ctx) and data manipulation/loading (-> parse_ctx)
- created dwarf2_parse_compilation_unit() for clarity
- added section structure to gather information about all ELF sections
  related to all dwarf2 sections (more to come)