v0.3.0: works now

• update to Derby 0.10.24
• update to Select2 4.0.12
• implemented search in single selection mode (dropdown/search)
• use npm's sortablejs instead of making Sortable an external dependency
• fixed event listeners and some bugs
• added a webpage with some demos using derby-standalone

Bugfixing

• views and styles without extension, let Derby's compilers decide
• filtering: don't allow input to be interpreted as regexp, be case-insensitive
• fix reordering of selections
• stop propagation of Esc
• improved the build system