Settings Screen and first 2 settings (#18)

* white sleep screen

* quicker pwr button

* no extra spacing between paragraphs

* Added settings class with de/serialization and whiteSleepScreen setting to control inverting the sleep screen

* Added Settings screen for real, made settings a global singleton

* Added setting for extra paragraph spacing.

* fixed typo

* Rework after feedback

* Fixed type from bool to uint8

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -274,6 +274,8 @@ void ChapterHtmlSlimParser::makePages() {
   currentTextBlock->layoutAndExtractLines(
       renderer, fontId, marginLeft + marginRight,
       [this](const std::shared_ptr<TextBlock>& textBlock) { addLineToPage(textBlock); });
-  // Extra paragrpah spacing
-  currentPageNextY += lineHeight / 2;
+  // Extra paragraph spacing if enabled
+  if (extraParagraphSpacing) {
+    currentPageNextY += lineHeight / 2;
+  }
 }