✨ Improvements

readme: add expected nfcapd folder structure, add installation instructions for CentOS 7 – thanks @Dona21!
processor: add processor interface, defaults to nfdump 47935e5 – thanks @nrensen!
frontend: add possibility to choose between step plotting (like original nfsen) or curve plotting dd83efa, 6d87d2d – thanks @nrensen!
frontend: remove "auto" output format, as it's the same as "line" acbe80e – thanks @nrensen!
frontend: stats dropdown: use better titles 377a5b8 – thanks @nrensen!
CLI/daemon: uses php from /usr/bin/env e61013a – thanks @panaceya!
CLI/daemon: log error message if RRD database could not be created 7b77995
CLI/daemon: fix deprecation introduced with PHP7.4 d4ed20e
update vendored libraries:
- jQuery v.3.2.1 to v3.5.0
- Ion.RangeSlider v2.1.7 to v2.2.0
- FooTable v3.1.4 to v3.1.6
- dygraphs v2.0.0 to v2.1.0

🔨 Bugfixes

readme: fix installation instructions – thanks @Dona21!
processor: fix passing empty arguments to nfdump 1c9f8f8
API: support previously non-working output format for record stats ca41fca – thanks @nrensen!
frontend: fix flows/stats csv output row count off by one fbc626a – thanks @nrensen!
CLI/daemon: fix broken port-specific data import 74e5872
CLI/daemon: can now be executed from any directory 9db5e5f
CLI/daemon: add missing use declaration 32047d6 – thanks @luizgb!