🐛 fix debugging/dump mixins

[philschatz]

This gets the debugging mixins to work again. Just add one ore more of these to the end of a book to dump out all the shapes/settings data:

@include debug_settings();   // Probably the most important
@include debug_settings_manifest();
@include debug_shapes();
@include debug_enums();

... and it'll print out something like this:

DEBUG: All available settings (last-added is on top) =>
DEBUG: === Clump Start ===
DEBUG: MeetTheAuthorNote:::_selectors : ".meet-author"
DEBUG: MeetTheAuthorNote:::group-border-color : (_ref: "colorMap:::meetTheAuthorColor")
DEBUG: MeetTheAuthorNote:::Title:::font-family : (_ref: "typography:::titleOption1Font")
DEBUG: MeetTheAuthorNote:::Title:::color : (_ref: "colorMap:::meetTheAuthorColor")
DEBUG: === Clump Start ===
DEBUG: TOC:::_selectors : "nav#toc"
DEBUG: TOC:::TocTitleWord:::color : (_ref: "colorMap:::neuroscienceHeaderColor")
DEBUG: TOC:::TocTitleWord:::border-bottom-color : (_ref: "colorMap:::neuroscienceHeaderColor")
DEBUG: TOC:::TocChapterNumber:::color : (_ref: "colorMap:::neuroscienceHeaderColor")
DEBUG: === Clump Start ===
DEBUG: BookRoot:::_selectors : ":root"
DEBUG: BookRoot:::BookRoot:::font-family : (_ref: "typography:::baseFont")
DEBUG: BookRoot:::BookRoot:::font-size : (_ref: "typography:::baseFontSize")
DEBUG: BookRoot:::BookRoot:::line-height : (_ref: "typography:::baseLineHeight")
DEBUG: BookRoot:::BookRoot:::color : (_ref: "colorMap:::fontBodyColor")
DEBUG: BookRoot:::BookRoot:::prince-image-resolution : "auto, 200dpi"
DEBUG: BookRoot:::BookRoot:::prince-background-image-resolution : 200dpi
DEBUG: === Clump Start ===
DEBUG: ColumnsFromTable:::_selectors : ".os-table"
DEBUG: === Clump Start ===
DEBUG: ParaIndented:::_selectors : "p.indented-text"
DEBUG: ParaCentered:::_selectors : "p.centered-text"
DEBUG: === Clump Start ===
DEBUG: ScreenreaderSpan:::_selectors : 'span[data-media~="screenreader"]'