Default DISP to TRUE for all In records

[AlexanderWells-diamond]

This PR will default the DISP field to TRUE for all In record types.

PythonSoftIOC In records never perform processing, and so are never given an opportunity to access the .VAL field, even if a caput has updated it. This means that while a caget call would return the new value, a record.get() call would not which would lead to confusion.

By setting DISP=TRUE we disable caput from changing the value and thus maintaining consistency between caget and record.get() values.

Note that it is possible to use caput to change the DISP field, but if users do this it's on them. I'm not sure there's any way to stop them doing this if they really want to.

This could be a breaking change, depending how well behaved people have been with In records. @MJGaughran gave the example of an In record being used as an input to a CALC record. And of course the more general use-case of someone just doing caput to an In record, when they probably should have been using an Out record.

[codecov]

Codecov Report

Merging #74 (0cda4cd) into master (5034531) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #74      +/-   ##
==========================================
+ Coverage   85.38%   85.39%   +0.01%     
==========================================
  Files          13       13              
  Lines         814      815       +1     
==========================================
+ Hits          695      696       +1     
  Misses        119      119              

Impacted Files	Coverage Δ
softioc/builder.py	95.91% <100.00%> (+0.04%)	⬆️

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