Add map2table func (take from pull.map with as.table=TRUE)

 - pull.map with as.table=TRUE now calls the new function
Forgot to export map2table
read.cross.tidy: avoid error caused by named args

(gen|phe|map)file being a *named* character vector
would cause do.call("read.table" to throw an error
Merge pull request #25 from aaronwolen/devel

Prevent error caused by passing named arguments to read.cross.tidy