Don't read and write from a file at once.

I think this is the cause for some errors with configs.
Fix bug in check_installed_packages.

`nil` is falsy.
Update toolbar's package descriptor.
Delegate PackageAttrs instance methods to the class.
Add a package for Hyperedit.
Update the package for Toolbar.
Add packages for RCS Build Aid and Science Alert.
Merge pull request #268 from shrx/master

Update README.md
Merge remote-tracking branch 'origin/master'
Add a package for PreciseNode.
Bump version.
Check for presence of path argument to `kosmos init`.
Merge pull request #273 from ucarion/check-args-kosmos-init

Check for presence of path argument to `kosmos init`.
update download link for mk2-cockpit-internals
Merge pull request #281 from icewind1991/update-mk2-cockpit-link

Update download link for mk2-cockpit-internals
add Planetary Editing Tools
add Texture Replacer
update Better Atmospheres
formatting
formating