included argument '...' into cross() and fit()

included '...' into cross(data, ...) and fit(data, ...) calls within the
node to allow further generality
included 'pars' argument in fit()

included 'pars' argument in fit(data,pars) to allow better control of
which covariates from the formula should be included
updates to m-trials
removed '...' argument
minor changes to brter
added jacknife option
minor change
added load data script
started m-fishnet
un-broke predict function
work in progress
added '...' to glmer$fit
minor changes
renamed files
updated evaluation in m-trials-brt
reconfigured brt fishnet and updated evaluation

reconfigured fishnet based on brt node evaluation and coded up cross
validation procedure
included predict.safe() function for fishnet

this allows sequential node execution within a fishnet without
over-writing existent covariate data
updated fishnet trials
added .gitattributes
work in progress