Implement log method for AskRealHandler (issue 2734)
Implement exp method for AskNegativeHandler
Merge pull request #2027 from skirpichev/2734-log-for-AskRealHandler

Implement log method for AskRealHandler (issue 2734)
Added WIP frame file
Added functions map_variables, removed __new__
Coded initialiser and time_derivative methods