mols2grid - Interactive molecule viewer for 2D structures

This release is a major change on the UI contributed by @themoenen, refer to PR#55 for the full list of changes:

• background_color="white" parameter added to display and save to control the background color of each cell.
• Property values displayed via subset or tooltip can now be copied by clicking them.

• Responsiveness: the grid as well as all UI components are now fully responsive, up until around ~415px wide. Smaller usage seems unlikely.
• n_items_per_page replaces the n_rows and n_cols parameters. The responsive CSS assumes results to be a multiple of 12, otherwise a gap is displayed at the end of the grid.
• Hover tooltips: now displayed when hovering the i icon, and anchored by clicking this icon.
• Save CVS: When exporting as CSV we now use a semicolon ; as delineator instead of a tab, this way CSVs are properly previewed on Mac.
• Templates: the pages/table templates and corresponding functions have been renamed to interactive/static for clarity.
• Parameters width and height have been renamed to iframe_width and iframe_height to be more descriptive.
• Improved the sorting UI to be more intuitive.
• You can now toggle between text/SMARTS search instead of having to click a dropdown.
• The checkbox menu icon was replaced with a more standard triple dot menu.
• The mols2grid-id is now permanently displayed next to the checkbox in the corner.
• SVGs are now rendered with a transparent background.
• The entire cell is now clickable, instead of just the tiny checkbox.
• Implemented some basic keyboard navigation: ENTER / ESC for selecting / unselecting, arrows and TAB for navigation.
• Copy to clipboard: this will now record a tab delineated text which is ready to be pasted into a spreadsheet, instead of the less useful dictionary format.
• The tooltip_trigger parameter has been removed since callback and hover functionalities don't overlap anymore.
• We're now automatically adding "img" to the subset instead of throwing an error.
• A smaller default font size (12px) makes the experience out of the box a bit more practical.

• Docstring now mention default values and some inconsistencies have been fixed.
• All UI elements are now neatly aligned and displayed on top so they're accessible without scrolling.
• Longer property values are now only truncated in the interactive grid, and broken into multiple lines by default in the static grid, as it is mostly meant for printing. A new parameter truncate lets you override the default truncating behavior.
• The tooltip display zone (around which the tooltip is displayed) is now the entire cell instead of only the image, so it never overlaps with any of the cell's data or functionality.
• When you download a CSV or SMILES file without any cells selected, you will now download data for all cells instead of an empty document.
• Parameter gap in static template didn't work.
• We no longer resize the iframe if a custom iframe_height is set by the display function.