feat: add new 'edgeLimit' option

[kangw3n]

fixed #352

added edgeLimit option to limit move event out of screen/container. default edgeRatio is 0.5 which based on moveable image.

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[codecov-io]

Codecov Report

Merging #429 (341a3ad) into master (0cecec2) will decrease coverage by 0.69%.
The diff coverage is 31.57%.

@@            Coverage Diff             @@
##           master     #429      +/-   ##
==========================================
- Coverage   75.29%   74.60%   -0.70%     
==========================================
  Files           8        8              
  Lines        1368     1382      +14     
==========================================
+ Hits         1030     1031       +1     
- Misses        338      351      +13     

Impacted Files	Coverage Δ
src/js/utilities.js	46.81% <0.00%> (-2.95%)	⬇️
src/js/methods.js	88.55% <100.00%> (+0.02%)	⬆️

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[fengyuanchen]

Good job, but still have some problems:

1. Cannot move to the edge when zooming out 200% or larger.
2. Test cases for the new options.
3. Usage documentation for the new options.
4. Don't push the bundled files.

[fengyuanchen]

As of v.1.9.0, you can use the move event to limit the moving range, here is an example:

https://fengyuanchen.github.io/viewerjs/examples/moving-range-limit.html

[kangw3n]

Brilliant Idea, Thanks a lot, maxOffsetPercentage do solve the first question as well, I'm just starting to rewrite and thinking the possibility to implement this feature on handler method like move and by then you've just done it.

BTW, should moving range limitation to be the default behavior of the plugin? I can't think of a use case that will allow to move image off of screen? So the question is, do we need to implement as an options or in other way is to made it as default behavior? I'm willing to help for moving it to the options method if you don't mind.

Anyway, You may close this PR anytime you like, thanks

[kangw3n]

As of v.1.9.0, you can use the move event to limit the moving range, here is an example:

https://fengyuanchen.github.io/viewerjs/examples/moving-range-limit.html

Minor bug detected, while zoomin around 300% and stick to edge of the screen, triggering toggle event (dbclick) may cause image out off canvas due to 100% centering issues,

This issue might be solved if we could dispatch move event along with zoomTo event or other similar event that will cause marginTop to moving the picture, perhaps?

[fengyuanchen]

Yes, the moving range limitation should be the default behavior but can be off if the user wants, so a new option defaults to true will be good.

[fengyuanchen]

In the given example, it will move the image into view if it is invisible after zoomed out now.