[TASK] Code style cleanups phase 1: Code smells
[TASK] Code style cleanups phase 2: Code style
[TASK] Code style cleanups phase 3: Doc comment consistency
[TASK] Code style cleanups phase 4: Parameter- and return types
[BUGFIX] Code style cleanups phase 5: References to missing variables
[BUGFIX] Code style cleanups phase 6: Undefined variables
[BUGFIX] Code style cleanups phase 7: Undefined and unused variables
[BUGFIX] Unintentional nullification of FlexForm ID
Merge pull request #116 from NamelessCoder/inspections

[TASK] Cleanups according to code inspections
[BUGFIX] Sheet not recognised by input and text fields

Fixes: #120
Merge pull request #123 from NamelessCoder/sheetmissing

[BUGFIX] Sheet not recognised by input and text fields