Fixed the map locations method to actually work when installed as a package
Additional functionality to the filters, implemented the args filters.

Previously args filters for nfilter and rfilter were not working, this update
should let these be called as arbitrary column names.
Added the mfilter method which can be used to do multiple equality groupings
Removed the mfilter method, integrated iterable checking on efilter and nfilter

methods to check if the values arguement is iterable, at which point
a slightly tweaked methodology will be used.
Doc strings, added ability to supply a custom map file to the map locations
check
The load_offerframe function can now, optionally, accept a user defined map