Always draw up to Nyquist frequency for discrete systems

[baggepinnen]

No description provided.

[JuliaControlBot]

This is an automated message.
Plots were compared to references. 11/11 images have changed, see differences below.
After pulling this PR, please update the reference images by creating a PR to ControlExamplePlots.jl here.

Difference	Reference Image	New Image
❌ 0.047
✔️ 0.011
✔️ 0.001
✔️ 0.001
✔️ 0.007
✔️ 0.003
✔️ 0.0
⚠️ 0.028
❌ 0.06
✔️ 0.0
⚠️ 0.017

[codecov]

Codecov Report

Merging #860 (2e57172) into master (a047432) will increase coverage by 90.90%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #860       +/-   ##
===========================================
+ Coverage    0.30%   91.21%   +90.90%     
===========================================
  Files           5        5               
  Lines         329      330        +1     
===========================================
+ Hits            1      301      +300     
+ Misses        328       29      -299     

see 3 files with indirect coverage changes