Mention limit if user attempts to encrypt file larger than 256 MB.

[keitharm]

There is a hard limit of 256 MB for strings in V8. Since we are converting to base64, that number translates to approximately a max file size of ~192 MB.

[keitharm]

Largest supported file is exactly 201,326,580 bytes for some weird reason. It is 191.9999885559 MB instead of 192 MB.

[keitharm]

64 bytes of meta data so actual max size of file is 201,326,516 bytes.

[keitharm]

|XX|XXXXXXXXXX|XXXXXXXXXXXXXXXX|XXXXXXXXXXXXXXXX|XXXX|
1-14901403241234567890abcdef1234567890abcdef25-- 48 chars of meta data = 64 bytes of base64 data = 16 pixels of meta data use - as padding

[keitharm]

New format:

|XXXX|XXXXXXXX|XXXXXXXXXXXXXXXX|XXXXXXXXXXXXXXXX|XXXX|
|version|timestamp|quickhash|checksum|len|

Version: 0xFFFF (4) Max version 65536
Timestamp: 0xFFFFFFFF (8)
Quickhash: 0xFFFFFFFFFFFFFFFF (16)
Checksum: 0xFFFFFFFFFFFFFFFF (16)
Len: 0xFFFF(4) Max length 65536

000158D1BCA41234567890abcdef1234567890abcdef8000 48 chars of meta data = 64 bytes of base64 data = 16 pixels of meta data