Add safe histogram notify functions
Merge pull request #60 from puzza007/safe-histogram

Add safe histogram notify functions
Fix histogram of type 'none'

* Before, after filling in the SIZE of the histogram, when adding new values the same element was deleted and updated all the time.
* Tests are included.
Merge pull request #61 from Lastres/fix_none_histogram

Fix histogram of type 'none'
Add histogram of type 'slide_sorted'

* This histogram is a simple sliding window of fixed size.
* Tests included.
Merge pull request #63 from Lastres/slide_sorted_histogram

Add histogram of type 'slide_sorted'