Add ability to manually enter coordinates in lat/lon and other coordinate systems

[gmaclennan]

Currently manually entered coordinates need to be in UTM WGS84. Coordinates for manual entry often come from an external GPS, which sometimes will be configured to show coordinates in a different format, most commonly Lat/Lon geographic coordinates. The manual coordinate entry screen should have an option to enter coordinates in a different coordinate system / projection, with geographic lat/lon WGS84 being the most common.

Question for users: Which is the most common way to see lat/lon?

1. Decimal Degrees (e.g. 30.56, -60.2)
2. Degrees, Minutes, Seconds (e.g. 30° 33' 36" N, 60° 12' 0" W)

Unfortunately there are lots of variations on these formats, which can lead to user error. E.g. coordinates in the southern hemisphere are sometimes represented as negative values, but sometimes as a positive value with the suffix "S" to indicate "South".

See also #420 that adds a settings option for how coordinates are displayed. This is separate to how they are entered but the entry format should default to the display format with the option to change entry format if needed.