* copied object-properties app from canvas-portal
- copied [object-properties](https://github.com/plotly/canvas-portal/blob/master/apps/object-properties/app.py) app from canvas-portal
- changed dash_table calls to work with updated API
- used px.imshow to visualize the label data

* fix None-type inputs before first interaction
- if callback inputs were not triggered by user interaction (i.e. when the app is just loaded), just return default values
- removed the suppression of callback exceptions

* dash-bootstrap-components for layout
- added dbc to requirements.txt
- added dbc stylesheet to app
- remove old stylesheets that are no longer needed
- moved app and content definition to the top of the file
- refactored `data` to `table` to avoid shadowed variable name from `highlight_filter` scope and for clarity
- broke layout into components and fit in dbc structure with annotations
- added plotly logo
- added a README.md file

* callback and region properties
- use new skimage region property computation function to construct data-table
- prevent call to `highlight_row` and `highlight_filter` callbacks at app start.

* informative hover
- pass data-table to image function
- match custom hover info with the currently displayed data
- also remove margins around figure

* removed label array cache and callback
- more explicit numpy datatype checking for the datatable columns
- added 1px margins (l/r) around .row elements to have datatable display fully
- added list of unique labels as cache
- removed label array Store and update from callback
- replaced functionality with list of currently visible labels
- some label related refactoring for clarity

* Performance improvement:
- converted label overlay to png using datashader
- added datashader to requirements.txt
- additional hidden scatter overlay for hoverinfo
- adjusted highlight_row callback to work with the scatter overlay

* CircleCI and better hover
- removed hoverinfo for background image
- made the content of the hover dependent on the selected columns in the datatable
- remove current label cache. Is not necessary because relevant information is available from table data
- fixed bug where contour was drawn based on row index rather than label.
- updated requirements.txt to pin CircleCI compatible versions (thanks @jonmmease)
- removed typecheck in image_with_contour since we supply the PIL objects

* Colormap
- dropdown to control what the color overlay is based on
- css change to give Cards margins on top

* Simplify overlay
- scatter trace is now opaque and gets colored based on the selected value. px.imshow color overlay is removed
- replaced datashader with matplotlib cmap call
- removed datashader and dependencies from requirements.txt
- trimmed requirements.txt to minimal requirements according to pipdeptree
- changed figure template to "simple_white" to hide the added margins, made axes invisible
- added initial value to dropdown menu that prevented the region contour from drawing correctly on app start (or before a dropdown value was explicitly set by the user)
- increased the line thickness of the region contour to stand out more against the colored scatter trace

* usability improvements
- added new modal and screenshot / gif
- added warning popup if colorscale is deselected (breaks things)
- pointed github button to correct repo
- added tooltips to datatable to better explain column selection
- annotated the image generator function
- cleaned up the imports