Fixed bug in metadata generation from the data model
Fixed a bug in _TO_JSON, where boolean instances were translated to their representation. But MongoDB have to use the instances, not the translations!
Reworked the derivedIndexes methods around BP::Model::Column and BP::Model::ColumnType, so text indexes are published
Improvements in batch insertions

BP::Loader::Mapper::MongoDB now uses MongoDB::BulkWriter instances, so it does not have to compute in advance the max number of documents it can send.

BP::Loader::Mapper now implements an asynchronous batch insert feature

Also batch-size configuration parameter is now honored in several places of BP::Loader::Mapper::ElasticSearch and BP::Loader::Mapper::MongoDB