Support for EPSG:3765 (regional alias for EPSG:4326)

[criskurtin]

Hi all!

I want to use Go Map!! for some local mapping while I'm outside with my iPhone or iPad. To do that, I'd like to have access to some WMS layers of the Croatian spatial development and general urban plans. Unfortunately, Croatian governmental WMS servers often advertise only EPSG:3765 and CRS:84, as is the case here: https://geoportal.zagreb.hr/Public/GUPZagreb_Public/MapServer/WMSServer?request=getcapabilities

EPSG:4326 is even advertised in the base layer, as it should be, but it's omitted from the nested layers.
3765 is just a regional realisation of 4326 so no reprojection is required between these. I wanted to add the support by myself (I still can), but I'd like to consult here first. I see there are two conditional statements in the code for 4326 at the moment, one for URL generation and one for converting tile to WMS coordinates. If 3765 is added, these statements would need to have 3765 added to them too. This could become messy if additional 4326 aliases would be added later on, so perhaps it would be good to separate these aliases into some list and replace the conditionals with something like if epsg4326Aliases.contains(projection).

I'd gladly make the service providers correct their WMS layer definitions, but that's probably not going to happen any time soon.

[bryceco]

if epsg4326Aliases.contains(projection)

I like this approach. Thanks for looking into this!