make `install_script` stanza more robust

* correctly (and leniently) parse values
* add test
Add PreForm.app 1.6.5

This is the first cask file submission for PreForm,
a desktop application to help prepare models
for Formlabs 3D printers.
Merge pull request #6334 from sherbondy/preform

Add PreForm.app 1.6.5
Merge pull request #6306 from rolandwalker/install_script_improvements

make `install_script` stanza more robust
Fix Transmit's shasum
Fix GDAL Framework's shasum
Update layout, facilitate updates for GDAL Framework
Merge pull request #6335 from ndr-qef/sha-mismatches

Fix shasums of Transmit and GDAL Framework
Update RethinkDB to 1.15.0
Merge pull request #6336 from ndr-qef/rethinkdb

Update RethinkDB to 1.15.0
Upgrade Manico to 1.4.1
Merge pull request #6339 from crainiarc/manico

Upgrade Manico to 1.4.1
Upgrade torbrowser to v3.6.6
Merge pull request #6340 from joelpurra/torbrowser-3.6.6

Upgrade torbrowser to v3.6.6
re-use version in abgx360
re-use version in accessmenubarapps
re-use version in actprinter
re-use version in adapter
re-use version in adium
re-use version in adobe-digital-editions