Re-implement LRU using a linked set data structure

It re-implements the LRU cache eviction policy using a
custom-built data structure that is basically a set with a
doubly-linked list running through its items.

Although the LRU policy worked well before, these changes make it
more maintainable and easier to implement LRU-based eviction
policies in future.
Add *remove* method to cache eviction policies

This method enables to remove a specified entry from a cache,
regardless of its position. In some cache eviction policies, e.g.
FIFO, it is not a O(1) operation.
Minor improvements to ResultSet class

This commit changes the signature of the constructor and the add
method to simplify its usage.
Enable plots with empty filters and arbitrary metric hierarchies

This commit improves the plot functions to enable plots without any
filters specified (which may be used for small resultset with
result sensitivity evaluated over a single parameter) and to
enable metric hierarchies of arbitrary lengths.
Add CDF plot function
Support handling of SIGABRT signal
Correct issue in script for reproducing ICN'13 results

In this script the line starting the actual simulations was
commented out, hence making the script not working.

This commit uncomments that line.
Fix typos and minor mistakes in the README file
Add script to print resultset dump

This script parses a resultset saved in pickle format and prints
a dump of all results to the standard output in a nicely-formatted
human-readable format.