refine comment

The constructors in each object file get merged during linking
so it's better to speak of shared libraries and executables
instead of object files.
print more information for tests

- OK or FAIL
- exception message (traceback) for failures
- test duration (in ms)
add implementation notes to dmain2.d
Fix bug 5842.

The bug is caused by rehash producing an AA with a zero-size hashtable
when called on an empty but non-null AA.
remove unused global variable
Merge pull request #577 from WalterBright/rm-unused-global

remove unused global variable
refactor src/rt/minfo.d
Merge pull request #568 from dawgfoto/betterTestRunner

print more information for tests
Merge pull request #575 from WalterBright/add-dll-notes

add implementation notes to dmain2.d
Merge pull request #578 from WalterBright/refactor-minfo

refactor src/rt/minfo.d
tweak message
Merge pull request #579 from monarchdodra/tweakRunner

tweak test_runner message
reduce repetition and sleep time for rwmutex tests
rewrite semaphore tests to reduce test time

- use core.atomic to reduce locking
reduce condition timeout wait
When AA is empty, rehash should revert it to original state.
Need to call GC.free on old table in AA rehash.
Merge pull request #556 from dawgfoto/refineComment

refine comment
Merge pull request #576 from quickfur/issue5842

Fix bug 5842.
Add forward range capability to AA .byKey and .byValue.