add welding example notebooks and some QOL code additions

[CagtayFabry]

No description provided.

[codecov]

Codecov Report

Merging #97 into master will decrease coverage by 0.06%.
The diff coverage is 96.42%.

@@             Coverage Diff             @@
##            master      #97      +/-   ##
===========================================
- Coverage   100.00%   99.93%   -0.07%     
===========================================
  Files           62       62              
  Lines         3049     3070      +21     
===========================================
+ Hits          3049     3068      +19     
- Misses           0        2       +2     

Impacted Files	Coverage Δ
weldx/transformations.py	99.46% <96.15%> (-0.54%)	⬇️
weldx/geometry.py	100.00% <100.00%> (ø)
weldx/utility.py	100.00% <100.00%> (ø)

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