JGCRI/gcam-core: GCAM version 4.4

GCAM version 4.4 Non-CO2 features and markets BECCS supply & demand updates New API for GCAM coupling Updated agricultural commodity prices and production costs Reduced carbon contents for managed forest & pasture Upgrade BaseX version Various bug fixes Please see the documentation on Getting started running GCAM for more information on getting started running GCAM. For most users they can download the Mac or Windows Release Package which contain everything they need to run the model and query results. For users who need to compile the model or change the XML input files should consult the documentation