JBIDE-17825 - Cannot initialize JBoss DND
JBIDE-18031: dispose listener to avoid WidgetDisposedError.
JBIDE-16891 - Add hover text to requirements table in New Project Example wizard
Update HMT wizard ID in proxy wizards
[JBIDE-18062] java.lang.ClassCastException in maven sourcelookup

replaced check for nul with instance of, so check covers both cases:
- null filtration
- class cast problem
[JBIDE-17909] Include Thym 0.1.0-SNAPSHOT into jbosstools TP

Update wizardId to correct thym wizardId.
JBIDE-18001 Cherry picked PR #273 to avoid dragging in unrelated changes to eclipse metadata files
JBIDE-17808: Mechanism to define and detect "families" of IU

* Plugins can contribute a "family" definition (such as earlyaccess,
supported,
blacklisted...) which lists the various ius for the given family
* A utility class allows to do request to compare current installation
with families
* Central editor shows when Early Access content is installed (computed
from family)
* An installation page is added to report Early Access IUs