UTM class to support other TM based national grids

[Polarbear]

It would be good if support for national TM projections could be considered in the generic UTM implementation currently going on.

This might be as simple as providing an interface for some core parameters.

E.g. I successfully hacked the current UTM 33 stub by using 8.0 as the centre meridian, and suddenly all my Irish TM references were orthogonal...

[stoecker]

Well, theoretically setting the meridian is already implemented, only currently the values are ignored when initializing the class. I had no time yet to fix that issue. Mainly it is to read and use the first value of the list given as argument (including validity checks).

[Polarbear]

currently in UTM.java, the zone and the UTMScaleFactor are wired at the beginning of the
class implementation, while the UTMCentralMeridianDeg is computed from the zone.

National TMs can have scale factors, central meridians and true/false origins different
from UTM, for example
​http://en.wikipedia.org/wiki/Irish_Transverse_Mercator#Comparison_of_ITM.2C_Irish_Grid_and_UTM

As I assume the core calculation is the same I thought all parameters could be kept adjustable.

In other words, keeping the generic TM calculation separate from the UTM specifics.

[stoecker]

See getPreferences() and setPreferences() at end of file (the two with TODO's inside). Currently only zone is handled as prefs (or not yet handled - TODO), others could be added. They will be presented in preferences dialog when UTM is choosen.

[Don-vip]

Closed as duplicate of #12186.
Irish Transverse Mercator (plus others) are managed in JOSM core since #12186