Improve storage and usage of the original map frame image (template)

[matthiasschaub]

Currently after the generation of a sketch map the map frame image (template) is stored in the database with its original resolution/size. Map frame images can be quite big (e.g. an A0 format). High resolution images for marking detection are not always needed. Especially in the case of an A0 map where the photo of the sketch map will be of lower resolution then the original map frame stored in the database.

Error like #212 are related to this.

Lets come up with better workflow to deal with this.

[mhhd2020]

#215 proposes limiting the max. resolution of map frame images stored in the database. A test of different parameter settings yielded a suitable value for this. Thus, this issue would be closed with #215, in case no other workflow is suggested