Add minimal support for fods

[jonadem]

See okfn/messytables#178

[codecov-io]

Codecov Report

Merging #3 into master will decrease coverage by 0.74%.
The diff coverage is 91.56%.

@@            Coverage Diff             @@
##           master       #3      +/-   ##
==========================================
- Coverage    97.7%   96.96%   -0.75%     
==========================================
  Files          12       13       +1     
  Lines         609      691      +82     
==========================================
+ Hits          595      670      +75     
- Misses         14       21       +7

Impacted Files	Coverage Δ
pyexcel_odsr/__init__.py	100% <100%> (ø)	⬆️
tests/test_fods_reader.py	100% <100%> (ø)
pyexcel_odsr/odsr.py	93.58% <87.5%> (-1.65%)	⬇️
pyexcel_odsr/messyods.py	92.56% <90.74%> (-1.05%)	⬇️

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[chfw]

Superb. Thanks for your PR.

[chfw]

due to the limitation of github, I could not upstream my changes to pending PR for messy tables.