Add various plots and analyses for PTM sites

[krassowski]

The changes implement following plots:

• rare mutations ratio & variability (in PTM regions vs outside)
• top ActiveDriver results (pan-cancer, disease, for specific cancers)
• gene ontology (with gProfiler)
• percent of sites in disordered regions (by site type)
• glycosylation motifs analysis

Various other fixes and improvements have been added.