Remove remaining traces of blockslib and blockseditor from the
source tree. They are AI1 specific and no longer used.
This removal will make fresh eclipse installs work without error.

See commit 4744a67c9a31d4996d68b3f9e1bc8dab82982248

Change-Id: I7f497a7ff5437ff5c13bc2376aa1b7205ed961cc