Releasing v4.2.0

* Refactored cell & formula logic out into separate files
* Added more tests to test things independently.

t/config/options.vim

@@ -0,0 +1,8 @@
+let g:table_mode_corner = '+'
+let g:table_mode_separator = '|'
+let g:table_mode_fillchar = '-'
+let g:table_mode_map_prefix = '<Leader>t'
+let g:table_mode_toggle_map = 'm'
+let g:table_mode_always_active = 0
+let g:table_mode_delimiter = ','
+let g:table_mode_corner_corner = '|'