* refactor: format all C files under nvim
* refactor: disable formatting for Vim-owned files:
* src/nvim/indent_c.c
* src/nvim/regexp.c
* src/nvim/regexp_nfa.c
* src/nvim/testdir/samples/memfile_test.c
Problem: Functionality for signs is spread out over several files.
Solution: Move most of the sign functionality into sign.c. (Yegappan
Lakshmanan, closesvim/vim#3751)
bbea47075c