abort if bad --jdt argument given to 'mx build; command
fixed JDT errors and warnings
update JLINE/JNR library dependencies
Merge
add assert to check format of debug info
fix comment typo
minor assembly tweaks
a few stronger asserts in snipppet expansion
mx: add option for forcing the usage of javac
gate: compile java with ECJ if available
use hotspot stubs for primitive arraycopy calls
Merge