docs won't build because of missing variables in CoreDDoc mode
Move prefix member function attributes to postfix
return Thread object in start method

- allows to write more concise code to start a Thread
Merge branch 'fixThreadDocs' into threadStartMethodChaining
Merge pull request #983 from 9rnsr/fix12931

Move prefix member function attributes to postfix
Merge pull request #972 from MartinNowak/fixThreadDocs

[trivial] docs won't build because of missing variables in CoreDDoc mode
Merge pull request #973 from MartinNowak/threadStartMethodChaining

return Thread object in start method