Generalized numberparsing. Added doubleoperations.

GenSolver can be said to use numbers as separators (as opposed to using
operators as separators).
NumberCreator now has a method bool isRelevantChar(char)
which will for most Solvers check whether the given char is a digit.
GenSolver will repeatedly call this method to figure out where
numbersequences end.
This makes integer-Solvers easy to implement -
the NumberCreators will just parse digits.
Decimal-solvers will however have to implement
dots and scientific notation through operations.
i.e.  a.b = a+b*10^-d, where d=digits(b)
and aEb = a+10^b.
These operators where added to StdOperators
and doubleoperations were added as examples.
Also IntGenSolverTest were changed accordingly (i.e. the new operators
were removed from the used IntGenSolver).
Debugged changes.