Fix whitespace in stream decoder

[nahne]

How does this PR improve libqp?

Without this PR, when decoding a quoted-printable stream, some spaces will get silently dropped, depending on stream chunk boundaries. With this PR, spaces and tabs are preserved as specified in RFC2045.

Steps to reproduce the issue

Run the tests in this PR. Without this PR, 3 tests will fail:

• Space at the end of a chunk
• Equals sign of a soft line break at the end of a chunk
• CR of a soft line break at the end of a chunk

Expected behavior

The decoded data should not change when the encoded data is provided in multiple stream chunks.

Actual behavior

Spaces and tabs are discarded, even though they should be preserved per RFC2045.

Related issues

We discovered the behavior when using nodemailer to parse quoted-printable encoded PDF attachments.

nodemailer #379: quoted-printable attachment missing some tabs might be related

[ornotnull]

my RE was simplier
/[\t ]*\=[^\n]?$/

possible it does not cover the all cases
this test failed:
not ok 4 - stream, space at end of chunk

[andris9]

Thank you. Will check this next week once I’m back from my vacation