Tracker - and more cleanup

A lot more under the hood updates, mostly correcting the removal of an application-wide list of sectors I did not need. I also added the 1st option: reset the sectors. This actually removes all the sectors and worlds from the local DB, resets all the ship sectors and worlds (now I realize I don't need a ship sector if I have a world - the world contains the sector. Maybe another correction in a bit).  It then reloads ALL the sectors for the 4 eras. Doing so of course broke the ship view - it was assuming we have valid values for the things I just cleared!  On the bright side, this should also correct the same issue when adding a new ship - something I had not thought of.

I also added a list of eras to the main app, so it is now centralized versus being in various places. The eras (M0, M1105, M1248 & M1900) are part of the API calls to the TravellerMap, so that you can get the UWP for the specific era. 1105 is of course the largest set of sectors; I think M0 only had about a dozen or so versus all of them for 1105.  I may have the options page show the count of sectors for each era, and maybe the list as well or something.

I've added a generic dialog class so that I can abstract user-enter dialogs a bit.  I've added that as I also added the image list table, and will allow you to load images for ships or worlds. I want to figure out the image carousel thing as I think that would be really cool, but realized I also wanted the user to be able to enter text for the images.

Throwing in one of the hex maps from my game - no images for the tracker since the UI has not changed much yet, and I like pictures.