modified the show_minima option in plot() method which marks each minima by a solid circle.

now it marks only minima whose id is listed in file 'mintoshow.dat'

if the file is not present, all minima are marked.

example mintoshow.dat:

$ less mintoshow.dat
3
4
5
9
16
18
$ ..
Merge branch 'master' of github.com:js850/PyGMIN