support for <palette sorted="true"> and <palette sorted="false"> in metamodel, which specifies whether to sort elements in a group and groups themselves by name or leave them in order specified by metamodel. Needed for TRIKStudio, where Smile and SadSmile blocks shall be adjacent. It also allows to fix some usability issues related to commonly used blocks are too hard to find in a palette.
Merge pull request #1198 from qreal/unsorted-groups

support for <palette sorted="true"> and <palette sorted="false"> in meta...