add more flexibility when exporting a relation to a GPX layer or file

[cmuelle8]

This patch is a major overhaul of the GPX conversion feature offered for relations by the RelationList dialog.

The input data is searched for the roles assigned to relation list members.

If and only if more than one role (usually: more than the empty role) is found, a dialog with four options is shown on how to deal with relation roles during the export process, these are:

• allow any role
• user-select roles to be considered
• allow preset-defined roles only
• ignore roles / treat all as empty

Userselection is an expert feature, because it may give unexpected results. It allows deselection of e. g. forward / backward roles that the WayConnectionTypeCalculator depends on to resolve directional variants of a route. Excluding members having these roles will impact the WayConnectionTypeCalculator's decisions for the remaining members and in consequence split the members in a different manner than if it would see the full data. A tooltip is provided to raise awareness to this.

Preset-defined option will look up the defined roles for the specific relation type being exported and any member with an (preset-wise) undefined role will be discarded during export.

Ignore roles can, amongst other use cases, be used to export all relation members of an otherwise bidirectional route, bypassing the WayConnectionTypeCalculator. It is less intended to produce a clean GPX for travel directions and contain possibly lots of disjoint segments, but offers the possibility to export all the relation geometry 1:1.

The patch is against an older revision and untested to apply cleanly to latest. Sorry for any inconvenience.

Screenshot of the dialog

[cmuelle8]

revamp export relation to gpx feature

[cmuelle8]

sample screenshot

[cmuelle8]

cp. to previous rev02rc adds additional option to sanitize output

[cmuelle8]

cp. to previous rev02rc adds additional option to sanitize output