Release v2.1.0 - Githubissues

[2.1.0] - 2021-08-16

sdk.core.identifiers.convertDSNPUserIdOrURIToBigNumber supports non-0x prefixed strings
sdk.core.utilities.serializeToHex for predictable hexadecimal to string values
Added createTombstone factory to announcements module
Added isTombstoneAnnouncement validator to announcements module
Added tombstone porcelain method to top level exports

Major rework of ActivityContent validations to log or throw informative errors when an ActivityContent is invalid, with a couple of other changes:
- An array of locations is no longer allowed; this will invalidate an attachment.
- Attachments MUST pass a minimal type check before further processing. For example if even one of its Link url hashes is malformed, it fails validation.
- If an attachment passes a type check, but it fails to meet requirements for what is supported by DSNP, it also fails validation. HOWEVER, attachments can have multiple Link URLs; only one needs to be supported by DSNP to be considered a valid attachment. See code documentation for details.
- If there is more than one attachment, but at least one is valid, it's considered a valid ActivityContent.
- New exported function for retrieving an array of valid attachments for an ActivityContent: requireGetSupportedContentAttachments Please see code documentation for details.
- Note on naming convention: anything beginning with 'require' will throw when failing the indicated action or validation. For example requireGetSupportedContentAttachments throws an error if there are attachments but none are valid.
- If you wish to simply check for type validity without having to catch errors, use isActivityContentNoteType and isActivityContentProfileType
Fixed a bug in duration validation.
Reworked ActivityContent validations to log or throw informative errors when an ActivityContent is invalid.

Fixed bug resulting in incorrect output from sdk.core.contracts.publisher.dsnpBatchFilter when passed Tombstone
Fixed a bug in duration validation.
Fixed a bug in DURATION_REGEX.
Fix bug in getRegistrationsByWalletAddress by normalizing address to checksum version