core skin upgrade

This version introduces multiple enhancements:

added bootstrap dark css, scripts and fonts
added scripts to show colorize code

Details of additions/deletions below:
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Added:      skin/core/default/css/base.css
Added:      skin/core/default/css/bootstrap_dark.css
Added:      skin/core/default/css/elusive-webfont.css
Added:      skin/core/default/css/elusive-webfont-ie7.css
Added:      skin/core/default/css/shCore.css
Added:      skin/core/default/css/shThemeDefault.css
Added:      skin/core/default/font/Elusive-Icons.eot
Added:      skin/core/default/font/Elusive-Icons.svg
Added:      skin/core/default/font/Elusive-Icons.ttf
Added:      skin/core/default/font/Elusive-Icons.woff
Added:      skin/core/default/js/base.js
Added:      skin/core/default/js/bootstrap.js
Added:      skin/core/default/js/bootstrap_dropdown_hover.js
Added:      skin/core/default/js/bootstrap_extend.js
Added:      skin/core/default/js/shBrushPhp.js
Added:      skin/core/default/js/shBrushXml.js
Added:      skin/core/default/js/shCore.js
Added:      skin/core/default/js/XRegExp.js