Make BEGIN and END tags easier to type

[bwbug]

For use-cases in which the shares will be distributed in hardcopy and manually typed for decryption, typing in the current BEGIN/END tags is unnecessarily cumbersome (especially with arbitrary requirements such as having to insert exactly one space character before S4 in the BEGIN tag but having no space after the ] bracket).

My suggestion is to simplify the tags, and to also allow some variability in the allowed use of whitespace within the tags (specifically, make all whitespace optional, by stripping whitespace before further parsing of the inputs). In addition, I would suggest not using the Base64 padding character (=) within the BEGIN/END tags, so that the line breaks can be made optional.

For example, I might suggest the following format:

[s4|v0.5|S4:YsVweIrrKfDotKXSTt4hGc2PZrwBJli1x8s25XkzlBkBLPc=]

If whitespace is stripped before processing, then optional line breaks (and/or indentation) could be inserted:

[s4|v0.5|S4:
    YsVweIrrKfDotKXS
    Tt4hGc2PZrwBJli1
    x8s25XkzlBkBLPc=
]

If you feel the need to keep the BEGIN and END keywords, then I would suggest making their use optional, as well:

[BEGIN|s4|v0.5|S4:
YsVweIrrKfDotKXSTt4hGc2PZrwBJli1x8s25XkzlBkBLPc=
|END]