Respect column position when jumping to tag

[andymass]

When jumping to declarations etc, include the column number in the target pattern. (Fixes #1)

• We would ideally want to use nvim's _get_line_byte_from_position to translate utf-16 position into column bytes, except that this function actually loads buffers unexpectedly. Instead, we use vim.str_byteindex directly in combination with:
  1. If the buffer is already loaded, simply read the line from the buffer
  2. Otherwise, read the line directly from the underlying file (this is the most expensive, though I haven't seen a problem yet)
• Uses %#c to target the column byte.

Considered alternatives:

1. Some might like the original line-only behavior, perhaps there should be an option, but not sure.
2. We could use a function call as the target of the tag instead of a pattern (similar to nvim's lsp.util.jump_to_location) which and only do the utf-16 to utf-8 conversion on the jump, which is potentially cheaper.

[weilbith]

Hey, I just remembered that there was this PR here. I finally returned to my own plugin and did some improvements. This included the usage of a column precise location. Reading up the PR description again it appears to solve the same issue. You might want to try if the latest version satisfy you? Did you had any other issues?