factorise and review the code changes used for CTD19

[fwyzard]

We need to factorise into independent PRs, review and eventually merge (part of) the developments used for Connecting The Dots 2019 (see #291 and/or the CMSSW_10_5_X_Patatrack_CTD19 branch).

History of PRs that are summed up there:

• Broken line fit #265 Broken line fit
• Speed Up Pixel Track fitting #266 Speed Up Pixel Track fitting
• Pixel Ntuple Fitters on cpu #269 Pixel Ntuple Fitters on cpu
• Add ability to save inner pixel triplets as well (if satisfy a condition) #270 Add ability to save inner pixel triplets as well (if satisfy a condition)
• make CUDA code compiling (and running) on CPU #271 make CUDA code compiling (and running) on CPU
• Pixel cluster size cut on gpu #276 Pixel cluster size cut on gpu
• Fix bugs in Riemann and BrokenLine fits #295 Fix bugs in Riemann and BrokenLine fits
• tune cuts to better reproduce 2018 HLT #296 tune cuts to better reproduce 2018 HLT
• make "vertex by density" default #297 make "vertex by density" default
• Triplet Cleaner by hits #304 Triplet Cleaner by hits
• Clean Digis and Hits #311 Clean Digis and Hits
• Make use of Cache allocator in "CA" #312 Make use of Cache allocator in "CA"
• implement RecHit SOA and move to new framework #322 implement RecHit SOA and move to new framework
• CTD19 developments for review and merging #324 CTD19 developments for review and merging
• CTD19 developments for review and merging (fixed) #329 CTD19 developments for review and merging (fixed)

[fwyzard]

Doing a proper review of over 100 modified files after the fact is, as expected, simply not possible.