Duration literals should be in small letters

[AndersHogqvist]

The document format feature change the duration literals to capital letters but according to IEC 61131-3 (and us) they should be in small letters. Example: T#1s becomes T#1S T#1ms becomes T#1MS

[Serhioromano]

I am releasing new version nor 1.12.12 where it is fixed. Even more it now lowercase those letters. I did not know that about standard. In few IDEs it is all capitalized I thought it is how it should be.