fix some compiler warnings and removes a debug printf from 1.12.0

[svigerske]

• removes a printf that is going to stdout, probably debug leftover
• initialize below_lower for compiler: avoids a maybe uninitialized warning
• make sure data_ is "used" also if HIPO_TIMING_LEVEL is 0: avoids an unused private field warning
• add missing #include statements: avoids missing-declaration warnings and ensures DataCollector is defined when compiling DenseFact.h
• make local functions static: avoids missing-declaration warnings, and allows inlining
• bring back comment line that was probably removed by accident

[jajhall]

Thanks @svigerske. These can merge to master, and we'll have to consider a patch release

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.06%. Comparing base (9fa8db6) to head (710aaa3).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2613   +/-   ##
=======================================
  Coverage   81.06%   81.06%           
=======================================
  Files         347      347           
  Lines       85219    85219           
=======================================
+ Hits        69082    69085    +3     
+ Misses      16137    16134    -3     

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[filikat]

The stuff in HiPO is fine. I was about to make some of these changes myself.

[galabovaa]

Looks good to me, thank you @svigerske!