encoded length macros for baseXX encodings
It can be useful to have macros that give the lengths of byte strings encoded with baseXX, particularly for declaring fixed-size buffers. Some use cases will need to include a terminating NUL, others not. These macros won't check for overflow, so nothing should pass untrusted inputs to them.
I propose macros named like BASE64_LEN() for the raw length and like BASE64_SIZE() for the length with NUL.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information