Grand hall -> Great hall and other text fixes

changelog.txt

dist/img/room/greathall/greathall.png

dist/img/room/greathall/imagemeta.js

docs/changelog_summary.md

docs/git/gitlog.txt

docs/update/readme_1_3.md

docs/update/readme_1_7.md

project/twee/activity/darko/structure/great_hall_gossip.twee

project/twee/building/building_template.twee

.../twee/building/templates/accomodation/BedchamberWing.twee

project/twee/building/templates/accomodation/Inn.twee

project/twee/building/templates/biolab/Biolab.twee

...ect/twee/building/templates/corruption/RitualChamber.twee

project/twee/building/templates/heal/Hospital.twee

project/twee/building/templates/heal/MoraleOffice.twee

project/twee/building/templates/heal/TraumaCenter.twee

project/twee/building/templates/hiring/HiringSquare.twee

project/twee/building/templates/misc/Classroom.twee

project/twee/building/templates/misc/Library.twee

project/twee/building/templates/misc/MissionControl.twee