Multiple changes.

- Raise an error if invalid options are passed to the constructor.
- Bugfix: Ensure drop() only removes the specified collection.
- Fix initializer double memory allocation.
- Fix key/data object allocation: make garbage collection safe.
- Move common macros to the global header file.

FossilOrigin-Name: 98d3016bd25921dead39d9c5474712766b56519d575bc8cd960932b3fbc16b69

experiments/thread_usage.rb

@@ -37,7 +37,6 @@ def run_bench( db, msg )
 			threads.map( &:join )
 		end
 
-
 		# Long running transactions require a mutex across threads.
 		#
 		x.report( "txn per thread:" ) do
@@ -78,4 +77,3 @@ run_bench( db, "Default database flags:" )
 db = MDBX::Database.open( 'tmpdb', no_metasync: true )
 run_bench( db, "Disabled metasync:" )
 
-