[WIP] Add support for parsing PDF pages in parallel

[phoewass]

Closes #20

Parse pages in parallel using multiprocessing library leveraging all the available CPUs.

Checklist:

• [x] Process in parallel using the library
• [x] Tests to process with and without parallel option
• [ ] Process in parallel using the CLI
• [ ] Update documentation

[codecov-commenter]

Codecov Report

Merging #237 (63161fe) into master (7709e58) will increase coverage by 0.07%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #237      +/-   ##
==========================================
+ Coverage   88.35%   88.42%   +0.07%     
==========================================
  Files          14       14              
  Lines        1571     1581      +10     
  Branches      358      359       +1     
==========================================
+ Hits         1388     1398      +10     
  Misses        128      128              
  Partials       55       55              

Impacted Files	Coverage Δ
camelot/io.py	100.00% <ø> (ø)
camelot/handlers.py	91.66% <100.00%> (+0.96%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 7709e58...63161fe. Read the comment docs.

[vinayak-mehta]

Why do we need to pass parallel as an argument to each test?

[phoewass]

I did this to avoid copying the tests and make sure that the new argument parallel does not break the API.

[maxdd]

Will this ever be merged or is camelot already mp?

[jgcmarins]

What is missing for this to be merged?

[hashangayasri]

Is this still WIP? What's preventing this from being merged?