Added RequestCache model
Use model to purge cache
Use model to delete database record
Use model to find request cache
Let request cache handle unserialization
The Isotope object now holds a reference to the current request cache
Added model method to find first limit for array of modules
Added methods to get filter or sorting config for array of modules
Added method to check if request cache is empty
Improved variable name
Use model to delete database record
Added model methods to set filter/sorting/limit for a module
Added class to build filter config using fluid interface
Added class to build sort config using fluid interface
Added toString methods to store filter/sort config in database
CS
Limits is an array, renamed methods and class variable
Implemented limit object
Store if request cache was modified
Request cache cannot be saved if it is modified