* add theme support of diagram
* add init mermaidTheme and vegaTheme when init muya
* export diagram
* update changelog
* add delete icon
* replace table toolbar icon to png
* replace icons in fromt menu and quick insert
* update format icons to png
* add theme support of diagram
* add init mermaidTheme and vegaTheme when init muya
* export diagram
* update changelog
* add delete icon
* replace table toolbar icon to png
* replace icons in fromt menu and quick insert
* update format icons to png
* update front icon hover color
* adjust format box icon size
* prevent some warning and rerender after change from source code
* remove debug code and replace image icon
* feat: basic use of code block by prism
* opti: remove codemirror from muya
* feat: add highlight to math and frontmatter
* feat: import and export in math block, html block, frontmatter, code block
* update: paragraph ctrl
* feat: copy and paste in new math block and html block
* feat: update code block style in dark theme
* feat: search and replace in code block
* fix: update menu item status when selection changed
* opti: optimization of updateCtrl divide it into clickCtrl and inputCtrl
* opti: search and replace in code block when no lang selected
* opti: copy paste in code block
* feat: insert paragraph before or after code block
* opti: change emoji.js to emoji.json
* feat: auto indent in code block
* opti: auto indent in code block
* opti: remove the use of snabbdom-virtualize
* fix: do not show format float box in code block
* opti: emoji picker
* update: delete some unused codes
* update: electron
* use a temp prismjs2 instead of prismjs