Nzshm-model

Added

- added backward_compatible property `fault_system_lts` with deprecation warning.

Changed

- Updated GMCM logic tree nrml files to reflect new OpenQuake class names and arguments for NZ NSHM gsims

Changed

- SourceLogicTree.from_branches() returns logic tree with Branch objects rather than FilterdBranch objects
- remove whitespace from logic tree file paths for compatability with OpenQuake

Added

- support caching of downloads
- build sources xml
- migration of version1 to version2 SLT
- iterate branches with SourceLogicTree
- build new SLT from branches iterable
- scripts/cli config command demonstrates building openquake config from an SLT

Added

- new scripts/cli module for PSHA related tasks, starting with fetch_sources
- psha_adapter pattern, with openquake package as first example

Changed

- new package structure for psha_adapter(s)

Changed

- refactor into resources package
- fix incorrect version info on v1.0.0 and v1.0.4 SLT json
- remove twine from project
- Revert "correlation values stored as sets"

Added

- new model class to make model definitions DRY;
- new nrml package to make classnames more compatible with GEM conventions
- gmm_logic_tree added to models
- SRM logic trees for various model hazard aggregations (in resources/SRM_LTs)