[INTERNAL] check for peak not found in filter 2
[INTERNAL] check for peak not found in filter 3
[INTERNAL] check for -1 indices and NaN intensities added
[INTERNAL] check for -1 indices and NaN intensities added
[INTERNAL] debug output fixed
[DOC] debug removed
[INTERNAL] minor fix
Merge pull request #930 from lars20070/fix/MultiplexFiltering

[FIX] added check for missing peaks to MultiplexFiltering