Replace pafrecord from_str with rust-csv deserialize [#8]

[esteinig]

• tiny degradation in parsing speed on large test file, speedup on small test file
• in favor of safer record parsing using rust-csv and serde deserialization
• simplifies PafRecord custom string parsing
• full test coverage

[esteinig]

Codecov Report

Merging #11 (b822aba) into main (13c2843) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #11   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         4           
  Lines          154       142   -12     
=========================================
- Hits           154       142   -12     

Impacted Files	Coverage Δ
src/cli.rs	100.00% <ø> (ø)
src/covplot.rs	100.00% <ø> (ø)
src/paf.rs	100.00% <100.00%> (ø)

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