Merge pull request #2 from brian-bot/master

move to nplr instead of nplogistic
Merge pull request #3 from brian-bot/master

change vignette name
nplogistic.R renamed to nplr.R
Merge branch 'master' of https://github.com/fredcommo/nplr
use props restored
modified warning message
removed commented lines
removed commented lines
added asymptote values in show method
improved params initialization & weights comput. in sdWeight
new arg 'silent', default is FALSE. Check if replicates if sdw is called
commented lines removed
stop if nplr returns constant fitted values: bad data
added: stop if x and y lengths differ, warning NA removed, if any.
inapropriate-pars stop alert moved to the top
completed, except for the example section
added link to nplr
removed link to nplogistic
doc partially added
typos