[Nice to have] Optionally save in ASCII PLY format

[Michael Ploujnikov]

Thank you for working on this sophisticated piece of software.

It would be nice if smvsrecon

smvs/app/smvsrecon.cc

Line 338 in 6a7d0c0

 mve::geom::SavePLYOptions opts; 

and simplify

smvs/tools/simplify.cc

Line 109 in 6a7d0c0

 mve::geom::SavePLYOptions opts; 

had an option to save their output in ascii PLY format. Set opts.format_binary = false based on some command-line argument?