Support vertical histograms

[t-bltg]

Fix #219.

[codecov-commenter]

Codecov Report

Merging #250 (9d74ab9) into master (ad7bca6) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #250   +/-   ##
=======================================
  Coverage   99.94%   99.94%           
=======================================
  Files          29       29           
  Lines        1702     1729   +27     
=======================================
+ Hits         1701     1728   +27     
  Misses          1        1           

Impacted Files	Coverage Δ
src/canvas.jl	100.00% <100.00%> (ø)
src/canvas/braillecanvas.jl	98.11% <100.00%> (ø)
src/graphics/bargraphics.jl	100.00% <100.00%> (ø)
src/interface/histogram.jl	100.00% <100.00%> (ø)

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