Memory used percent graphe can be misleading

[walidlotfi]

Hello,

I love your tool, espescially the functionnality to merge multiple sar files and generate a single graphe.

I have a suggestion, if possible adding a graphe in the memory section or modifying the "memory used graphe" behavior as currently it shows the %memused which may be misleading sometimes as it contains the cached memory. A graphe showing both seperatly or not based on %memused would be interesting.