Pickling UDPipe #387

[s-alexey]

Issue

Even though this will fix the issue with pickling UDPipeLemmatizer the fact that Corpus.used_preprocessor is traveling around up to Network from Distances is quite suspicious.

Description of changes

updipe.Model is not compatible with pickle protocol thus should be manually loaded.

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #447 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #447      +/-   ##
==========================================
+ Coverage    85.9%   85.98%   +0.08%     
==========================================
  Files          34       34              
  Lines        1937     1941       +4     
  Branches      331      331              
==========================================
+ Hits         1664     1669       +5     
+ Misses        233      232       -1     
  Partials       40       40

[ajdapretnar]

This no longer happens with the latest Network add-on master, but I am sure it doesn't hurt to have this handled since it avoid problems downstream.