Lexd files without final newline

[mr-martian]

Due to the various whitespace controls in the lexd grammar, comments are currently required to be newline-terminated. This breaks if there is a comment that ends in EOF rather than \n.

Options:

• wait for Grammar construct to match EOF / end of file / document tree-sitter/tree-sitter#160
• wait for Rule to disable extras matching tree-sitter/tree-sitter#931 and restructure a bit
• restructure to look for newlines at line beginnings instead of line ends (a bit weird but it might word)

(moved from #4)

[TinoDidriksen]

I would strongly argue any text file that doesn't end in \n is malformed. All lines must be terminated, also the last one.

[mr-martian]

And apertium-lint https://github.com/apertium/apertium-lint/blob/master/linters/file_linter.py#L81 currently treats it as such.