bugfixed upsampled srcdiff image
major new tools and updates

* external masses working
* better ext_mass ui element
* better ruler2 ui element
* ratio arcsec/px = pxScale now parameter
* tooltips
* keyboard shortcuts 1234,qw,asd,zxc
* naming and new placement of output images
* div svg ui bugfixes, strange behaviour when ruler ontop...
* added tools app section in django
* 1. tool: resultdatatable

needs full update:
- backend: yes
- database: no
- html: yes
- server url config: yes
pxScale fix
added inputpoints overlay
bugfix
restructred inputpoint painting
changes
backmerge master