Remove duplicities in code

[petrlicman]

Is your feature request related to a problem? Please describe.
There are some methods that just duplicate of another one, or doing exactly the same logic as another method and do not have any another purpose. Check and find such methods and remove them, replace theirs calls by one method.

For instance, there is no difference between those 3 methods, ToBooleanSafe, ToBoolean, ToNullableBoolean:

(not needed to have "bool?" as return type, of course it is possible to assign "bool" to nullable "bool?"