Extend tests and use Mineunit badges

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Click for detailed source code test coverage report

### Test coverage report for Metatool API sources: ``` File Hits Missed Coverage ----------------------------------------------------- api.lua 157 89 63.82% command.lua 4 43 8.51% formspec.lua 0 156 0.00% init.lua 0 8 0.00% settings.lua 83 9 90.22% util.lua 37 15 71.15% ``` ### Test coverage report for Containertool sources: ``` File Hits Missed Coverage ----------------------------------------------------- init.lua 56 10 84.85% nodes/common_defaults.lua 33 14 70.21% nodes/digilines_chest.lua 11 7 61.11% nodes/more_chests_shared.lua 10 4 71.43% nodes/technic_chests.lua 61 19 76.25% nodes/technic_injector.lua 23 5 82.14% ``` ### Test coverage report for Tubetool sources: ``` File Hits Missed Coverage ----------------------------------------------------- init.lua 19 3 86.36% nodes/any.lua 22 4 84.62% nodes/injector.lua 10 24 29.41% nodes/mese_tube.lua 25 25 50.00% nodes/sand_tube.lua 12 7 63.16% nodes/teleport_tube.lua 38 36 51.35% ``` ### Test coverage report for Sharetool sources: ``` File Hits Missed Coverage ----------------------------------------------------- init.lua 47 44 51.65% nodes/any.lua 75 57 56.82% nodes/book.lua 23 15 60.53% nodes/digiline_global_memory.lua 24 2 92.31% nodes/mapserver.lua 17 15 53.12% nodes/missions.lua 10 15 40.00% nodes/travelnet.lua 34 165 17.09% ```