Fixed Screwdriver

Fixed a Bug which causes doors (if locked or not) to be opened by the
screwdriver. It now makes a check if you are on valid ground.
Added TNT workaround

Added a quick workaround to avoid TNT set near claimed areas to destroy
partial buildings or landscapes with the TNT exploit.  Since overwriting
the registered node functions seem not to work as expected, used the
landrush own routines for this 'fix'
Merge branch 'master' of https://github.com/fairiestoy/landrush into fairiestoy-master