Memory leak (especially in X server)

[wellenvogel]

When the oensec_pi plugin closes a chart it creates a memory leak by not destroying the member m_pCloneBM of oSENCChart.
It seems that on the program side itself this leak is rather small but on the Xserver side it is 0.3MB (measured on an ubuntu bionic with Xvfb). So after long runs there is a chance that the Xserver starts to consume more and more memory - especially if the cache size is small and charts are frequently closed. This is especially a problem on systems with low memory (like the raspberry).
Deleting the member in the destructor solves the problem.
There still seem to be smaller leaks (factor 10 smaller) - but I did not investigate on them.

[bdbcat]

Corrected in source, not yet released to catalog