feat: introduce encryption result version

[mikesposito]

This PR introduces a version property in the EncryptionResult object. Adding a version to the encryption result object allows the use of different decryption algorithms or configurations based on it.

The current implementation (prior to this PR) is classified as version 1.0, and for EncryptionResult objects that don't have a version property at all, version 1.0 is inferred: this ensures that the decryption methods of this library can still decrypt old versions.

Moreover, this PR also adds a 2.0 version, where the encryption key is derived with increased iterations.

When encrypting, it is now possible to specify the version (defaults to 2.0).

Changes

• BREAKING: Added iterations optional argument to keyFromPasswordwith 600000 as default value
• CHANGED: Added optional version argument to encryptWithDetail with 2.0 as the default value
• CHANGED: Added optional version argument to encryptWithKey with 2.0 as the default value

[mikesposito]

Closed in favor of #49