Fix stripping chars from vifm-help.txt on OS X

Thanks to Stephen L. Holtz (a.k.a. stephenholtz).
Merge branch 'fix-vifm-help-on-os-x'

Fix stripping special sequences from vifm-help.txt on OS X.

Thanks to Stephen L. Holtz (a.k.a. stephenholtz).

Fixes #48.