Ignore Qt Creator and Eclipse files
Move tests/assert into separate subdirectories

Update CMake configuration to properly set building dependencies for
test targets (ATM, enabled for empty and sqlite3 only).
Closes #199.
Make a few additional CMake configuration updates and improvements in
handling external dependnecies/libraries.
Enable other tests in tests/assert

Update related to #199.
Fix includes to point to backend headers in subdirectories

wip: updates related to #125 and #199 for further cleanup in CMake
configuration is advised to fully use buried headers and change includes to:
<soci/soci.h>
<soci/mysql/soci-mysql.h>
etc.
Fix copy-n-paste error in CMake macro parameter name
Fix Firebird includes of private headers
Fix paths to ODBC test DSN files
Move ODBC test DSN files to new tests location
Revert CMake setup for ODBC DB2 test
Delete obsolete src/<backend>/test directories

All the content has been moved to tests/assert/<backend> as part of #125