pmemkv version 1.5.0

New features:

• Introduce (optional) caching layer in radix engine. It can be enabled via config parameters
• Add new config's flag - 'create_if_missing' to address the missing functionality. If set, pmemkv tries to open the pool and creates it if missing. It's mutually exclusive with 'create_or_error_if_exists' flag

Bug fixes:

• Return correct status for wrong parameters in pmemkv_config_from_json (instead of failing on assert)
• Fix iterator::key() implementation to return the whole key, not only the part up to the first null-terminator
• Return correct status from memkind-based engines on open failure

Other changes:

• Add alias 'create_or_error_if_exists' for 'force_create' config's flag and deprecate the latter one. The old flag can still be used and it behaves with no difference. It's discouraged from using, though
• Add dram_vcmap engine based on tbb::concurrent_hash_map for benchmarking purposes
• Switch default CMake's build type from "Debug" to "RelWithDebInfo" when compiling from sources - it's relevant for a GitHub users (who may e.g. run some benchmarks)