The random points on lines algorithm does not respect the (global) minimum distance between points

[havatv]

Describe the bug
When specifying a minimum distance between the generated points, the minimum distance is only respected for each line feature, not globally.

How to Reproduce

Run the plugin on a line layer with a large number of points per feature and a reasonably large minimum distance.

QGIS and OS versions

QGIS version	3.13.0-Master	QGIS code revision	a652c35
Compiled against Qt	5.9.5	Running against Qt	5.9.5
Compiled against GDAL/OGR	2.2.3	Running against GDAL/OGR	2.2.3
Compiled against GEOS	3.6.2-CAPI-1.10.2	Running against GEOS	3.6.2-CAPI-1.10.2 4d2925d6
Compiled against SQLite	3.22.0	Running against SQLite	3.22.0
PostgreSQL Client Version	10.12 (Ubuntu 10.12-0ubuntu0.18.04.1)	SpatiaLite Version	4.3.0a
QWT Version	6.1.3	QScintilla2 Version	2.10.2
PROJ.4 Version	493
OS Version	Ubuntu 18.04.4 LTS
Active python plugins	pluginbuilder3; plugin_reloader; SDEllipse; qgisnetworklogger; qgis_resource_sharing; LineDirectionHistogram; processing_taudem; processing_r; MetaSearch; processing; db_manager

Additional context