Fixed user setting were being ignored after first RequestInformation.

The settings cache used in RequestInformation was never overwritten. Therefore,
user settings were ignored after setting AutoDetect, calling
RequestInformation and then turning AutoDetect off. This is a common pattern
in ParaView since it calls RequestInformation with default settings in order
to get array names. Fixed by deleting the cache when the object is modified.

Change-Id: Ibc832726cf1ba8a5839770eae5fae2b893c00357
Merge topic 'fix_plot3d_issue' into master

0c786978 Fixed user setting were being ignored after first RequestInformation.