This makes the code in the various toolbox more generic. The arguments
of the text to insert are each replaced by a Ion::Charset::Empty.
These Empty chars are used to create layouts in ExpressionLayoutFields,
and to compute the position of the cursor in other fields, before being
removed.
Change-Id: Ie81c1e394b06fef2ab801ccff919d6550f70ec30
Else, there would be a problem with sequence_toolbox, where not all
toolbox leaves are message trees.
Change-Id: Ib4968aad37f6a835b1ea4d77efac2ae1bd19c7ce
The cursor now goes either after the first open parenthesis or at the
end of the command.
Fixed z.real and z.imag.
Change-Id: I46ca3be0415832fd91273ca7fed12ed3d6f125dc
