FIX - XML Module failure when no checksumming

[carlwilson]

• removed unused configuration extensions;
• made ChecksumInputStream _cstream private to ModuleBase to avoid abuse by other modules;
• XmlModule now forced to use _dstream so works without checksumming engaged; and
• added defensive exit to change directories in bash scripts.

[codecov]

Codecov Report

Merging #427 into rc/jhove-1.22 will decrease coverage by 0.13%.
The diff coverage is n/a.

@@                 Coverage Diff                 @@
##             rc/jhove-1.22     #427      +/-   ##
===================================================
- Coverage            48.81%   48.67%   -0.14%     
+ Complexity             958      954       -4     
===================================================
  Files                   55       55              
  Lines                 7666     7659       -7     
  Branches              1394     1393       -1     
===================================================
- Hits                  3742     3728      -14     
- Misses                3445     3458      +13     
+ Partials               479      473       -6

Impacted Files	Coverage Δ	Complexity Δ
...main/java/edu/harvard/hul/ois/jhove/JhoveBase.java	42.85% <ø> (+0.06%)	42 <0> (ø)	⬇️
...ain/java/edu/harvard/hul/ois/jhove/ModuleBase.java	50.69% <ø> (ø)	70 <0> (ø)	⬇️
.../java/edu/harvard/hul/ois/jhove/ConfigHandler.java	60% <ø> (+0.33%)	26 <0> (-1)	⬇️
...in/java/edu/harvard/hul/ois/jhove/Checksummer.java	67.79% <0%> (-11.87%)	13% <0%> (-2%)
...edu/harvard/hul/ois/jhove/ChecksumInputStream.java	68.42% <0%> (-10.53%)	9% <0%> (-1%)

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