coveralls upload should not fail the CI build

- swallow error code
Replace lalloc() with xmalloc()
No OOM error in make_filter_cmd()
Delete the lalloc() function
update CONTRIBUTING.md
Update CONTRIBUTING.md with current info

- Finish what @ashleyh started.
- Add section for Getting Started with Neovim.
- Add section for commit messages.
- Trim down on wording to keep it short.
Remove crypt.{c,h}
Remove blowfish.{c,h}
Remove from ex_docmd.c
Remove from main.c
undo.c: remove `fwrite_crypt`
undo.c: Fix `serialize_header`
undo.c: Fix `u_write_undo`
undo.c: Fix `u_read_undo`
undo.c: Remove `read_string_decrypt`
Remove from option.c
Remove from memline.c
Remove from fileio.c
Remove blowfish includes
Remove leftovers