Improve string representation of RecordWrapper

[AlexanderWells-diamond]

The returned string is the full DeviceName:RecordName.

Previously the string representation would be lost when builder.LoadDatabase() is called, as the builder instance is removed and so str__ returns None.

The __device is not removed at any point, and so can always be safely used to fetch the full name.

Fixes #129

[codecov[bot]]

Codecov Report

Merging #130 (289897e) into master (860f59c) will increase coverage by 0.10%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #130      +/-   ##
==========================================
+ Coverage   87.34%   87.44%   +0.10%     
==========================================
  Files          14       14              
  Lines         996      996              
==========================================
+ Hits          870      871       +1     
+ Misses        126      125       -1     

Impacted Files	Coverage Δ
softioc/pythonSoftIoc.py	92.06% <100.00%> (+1.58%)	:arrow_up:

[github-actions[bot]]

Unit Test Results

     15 files  ±  0       15 suites  ±0   26m 51s :stopwatch: +27s    272 tests +  1     256 :heavy_check_mark: +  1    16 :zzz: ±0  0 :x: ±0  4 080 runs  +15  3 490 :heavy_check_mark: +15  590 :zzz: ±0  0 :x: ±0 

Results for commit 289897ee. ± Comparison against base commit 860f59c2.