Resolves: #2083 colon separated integers for preconditioning

[lberti]

Presently, via the function parseFieldsDef in feel/feelalg/datamap.cpp, one can only read lines of comma-separated integers, as in

0->(1,2,3,4,5,6,7,8,9,10,11),1->(1,4,7,10).

In order to simplify data insertion, one can now read colon-separated integers as in

0->(1:11),1->(1:10:3),

and obtain an equivalent result as in 0->(1,2,3,4,5,6,7,8,9,10,11),1->(1,4,7,10).

[vincentchabannes]

@lberti @prudhomm I think the notation is not correct (or not standard). The last integer is the stop criteria, not the last. For example, I use this feature in toolbox. I think it same in python/matlab.