add: gitignore
add: crypto ontology
Merge pull request #1 from ni-/enh/dicom-mappings

Enh/dicom mappings
rf: rename to ttl
update readme
add: initial doc on prov import
add: prefixes and imports
add: allow catalog file
add: example serializations
add: dicom terms as data properties
add: dicom namespace and replace neurolex URI
add: temporary title and date
upd: extracting terms from nlx
add: IAO_0000115 definition