Optimize name column chopping with `wcwidth`

[pyroscope]

• Might need configure test for wcwidth (skip that if it compiles on Precise)
• Add to canvas rendering code
  • need to check how to easily decode UTF-8 sequences into code points
  • do a pre-check for pure ASCII, then just use substr
• Inserting spaces or bumping the column position might also be needed
• Find an adequate test case that causes visual defects with the existing code

See also https://github.com/rakshasa/rtorrent/issues/755

[q3cpma]

Oi, didn't see this. If you want a test, look at https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms for double width examples.

[q3cpma]

If you want, I made a simple tool doing the job (http://repo.or.cz/misc-tools.git/blob/HEAD:/mbcut.c). You could copy paste some of it.