fix autoscrolling for non standard orientations

[casvanluijtelaar]

fixes #9

• fix auto scroll for different Direction
• fix auto scroll for reverse scroll

[codecov]

Codecov Report

Merging #13 (c4ed573) into master (6a2c590) will decrease coverage by 1.26%.
The diff coverage is 48.57%.

❗ Current head c4ed573 differs from pull request most recent head a55b5e2. Consider uploading reports for the commit a55b5e2 to get more accurate results

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
- Coverage   81.26%   80.00%   -1.27%     
==========================================
  Files           2        2              
  Lines         491      510      +19     
==========================================
+ Hits          399      408       +9     
- Misses         92      102      +10     

Impacted Files	Coverage Δ
lib/src/reorderable_grid.dart	80.85% <45.45%> (-1.78%)	⬇️
lib/src/reorderable_grid_view.dart	76.99% <100.00%> (+0.41%)	⬆️

---

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 6a2c590...a55b5e2. Read the comment docs.