Fix bar overlap bug when tick fit is false

[rkrabek]

Partial fix for issue #1386

If tick fit is set to false and there are many values, the bars overlap because the bar width is currently calculated based on how many ticks there are instead of the data points.

[codecov-io]

Codecov Report

Merging #2306 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2306      +/-   ##
==========================================
+ Coverage   74.92%   74.95%   +0.03%     
==========================================
  Files          51       51              
  Lines        4227     4233       +6     
==========================================
+ Hits         3167     3173       +6     
  Misses       1060     1060

Impacted Files	Coverage Δ
src/shape.bar.js	100% <100%> (ø)	⬆️
src/axis.js	95.77% <100%> (+0.01%)	⬆️

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[panthony]

@rkrabek Thanks for your contribution. Could you add some to tests to ensure this is actually fixing something?

I tried your fix with the following config:

http://jsfiddle.net/moeumaj7/3/

And in this case it's actually break the display.

[rkrabek]

@panthony Sorry for the delayed response, I've been super busy at work. I've updated the PR to include tests for bar width when tick fit is false.

The config that you provided: http://jsfiddle.net/moeumaj7/3/ fails with my patch for the same reason it fails when you switch tick/fit to true as shown here: http://jsfiddle.net/ox76hL53/
For the sake of not introducing regressions, I've updated the code to take the max of ticks or unique x values so that should address the break in the config you provided.

This patch aims to fix this scenario (with or without the null data points): http://jsfiddle.net/dtttsa9d/