implement --transparency/-x at the command line

Closes #100
don't convert float to bool
reorder options in manpage and --help
fix whitespace indent level

@Xecantur: please don't mess with the whitespace
Make Pseudo Transparency Work!

Added pseudo_transparency bool in info_config struct, and changed set_opacity
to use it for vte_set_background_transparent().
Merge pull request #102 from numerical/master

Fix pseudo transparency