Fixes for armor and cleartext messages parsing

[ni4]

Sorry for putting a bit different things into the single pull request.
So this one:

• fixes misc armoring/dearmoring processing problems
• fixes partial data length processing in dearmoring code
• fixed cleartext signing/verification
• adds CLI tests for armored and cleartext stuff

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@5bcf8b7). Click here to learn what that means.
The diff coverage is 72.5%.

@@            Coverage Diff            @@
##             master     #423   +/-   ##
=========================================
  Coverage          ?   52.27%           
=========================================
  Files             ?       49           
  Lines             ?    13101           
  Branches          ?      162           
=========================================
  Hits              ?     6849           
  Misses            ?     6202           
  Partials          ?       50

Impacted Files	Coverage Δ
src/lib/writer.c	48.27% <60%> (ø)
src/librepgp/reader.c	66.81% <76.66%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5bcf8b7...4f38848. Read the comment docs.

[ronaldtse]

Thanks for the improvements!

[ronaldtse]

@ni4 I feel that the characters like "- " and '\n' should be assigned by some definition.

[catap]

Looks good but I agree with @ronaldtse remarks about "- ".

[ni4]

@ronaldtse @catap Thanks, you are right. Will update PR with defines

[ni4]

@ronaldtse @catap Done. If somebody have idea of better place for those defines (so we can use them from repgp/reader.c) you are welcome to share.
Otherwise feel free to merge it

[ronaldtse]

LGTM, yet one of the CLI tests are failing due to GnuPG problem... can it be fixed?

[ni4]

@ronaldtse Sorry, only now found your message. Sure, I remember about this issue and will fix in one of the subsequent PRs with CLI tests update.