Add from to sequence diagram conditions

[bkryza]

Fixes #154

[codecov-commenter]

Codecov Report

Merging #174 (13aa1d7) into master (ecf07b9) will increase coverage by 0.01%.
The diff coverage is n/a.

❗ Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the GitHub App Integration for your organization. Read more.

@@            Coverage Diff             @@
##           master     #174      +/-   ##
==========================================
+ Coverage   86.28%   86.30%   +0.01%     
==========================================
  Files         112      113       +1     
  Lines       11143    11380     +237     
==========================================
+ Hits         9615     9821     +206     
- Misses       1528     1559      +31     

Files Changed	Coverage Δ
src/cli/cli_handler.cc	43.71% <ø> (+0.03%)	⬆️
src/common/generators/generators.cc	0.00% <ø> (ø)
src/config/config.h	100.00% <ø> (ø)
src/config/option.h	97.22% <ø> (+0.55%)	⬆️
src/config/yaml_decoders.cc	87.04% <ø> (+0.14%)	⬆️
src/config/yaml_emitters.cc	90.18% <ø> (+0.09%)	⬆️
...gram/generators/json/sequence_diagram_generator.cc	95.79% <ø> (+0.01%)	⬆️
.../generators/plantuml/sequence_diagram_generator.cc	95.28% <ø> (+0.43%)	⬆️
src/sequence_diagram/model/diagram.cc	85.60% <ø> (-3.15%)	⬇️
src/sequence_diagram/model/diagram.h	100.00% <ø> (ø)
... and 2 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more