Add agwrite function

[eliascarv]

No description provided.

[codecov-commenter]

Codecov Report

Merging #31 (790b923) into master (6dfe2fa) will decrease coverage by 1.35%.
The diff coverage is 87.87%.

❗ Current head 790b923 differs from pull request most recent head 8347a0e. Consider uploading reports for the commit 8347a0e to get more accurate results

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@@            Coverage Diff             @@
##           master      #31      +/-   ##
==========================================
- Coverage   93.60%   92.25%   -1.35%     
==========================================
  Files           3        4       +1     
  Lines         125      155      +30     
==========================================
+ Hits          117      143      +26     
- Misses          8       12       +4     

Impacted Files	Coverage Δ
src/GeoTables.jl	96.00% <66.66%> (+0.16%)	⬆️
src/agwrite.jl	90.00% <90.00%> (ø)

... and 1 file with indirect coverage changes