Fix mapping variables in process models

It is horrible ui trying to pick a process variable to save into particularly in records where scrolling through lists of inputs is extremely painful especially if it is a down a relationship or two. The order always seems strange and near impossible to find what you need. It needs a complete redesign! I probably spent about 5 mins today trying to save a variable as every time I got close it would loose focus on the relationship and I would have to start again.