Fixed an issue that caused some comment keys to mirror the value of their predecessor
Added a regression test for the previously fixed issue
add debug output to check_error test
fix some todos in tests
implement isNull
add isNull tests
fix wrong exception text
swig-python: fix kdb test

tearDownClass is a class method with 1 argument
swig: fix add_subdirectory statement
fix #145 correctly

now kdbGet() on empty files will be avoided
also fixes kdbGet() syncbits on reusage
follow-up #145 for fixing all plugins+testing
Revert "fix #145" (wrong fix)

This reverts commit ce4811e31af0030649292b47683651e5db0485da.
Fix #151

Merge branch 'fberlakovich-hosts-comments-bug'