dev
Moved position info from ItemBases to AbstractLayoutItem.
Show spoilers in shared media overview.
Replaced some qsl with u""_q literal.
Moved generic document preview info to separated file.
Removed layout.cpp/h.
Spread some style entries from basic style.
Removed some unwanted include directives of styles in header files.
Moved layout utils to td_ui.
Moved text selection utils to td_ui.