changes to documentation

minor changes to documentation files related to
some of the utility functions and the variance estimation routines
added require(functional)

this appears to be necessary because one of the functions is
defined using Curry from the functional library
changes to RDS variance estimation

refactored and rewrote both of the bootstrap routines that
are used with RDS samples
updates to vignettes

added two new vignettes, generalized_scaleup and rds, which
will have details on those two methods. also added some content to
network_scaleup, and some very minor changes to getting_started.
none of the vignettes is finished yet.