* Fix tsconfig scopes affecting html.js
Since it's quite hard to use a DOM library type there, remove the type
entirely.
* Remove environment variables check
Nothing is using them anymore. It can be added back if needed later.
* Refactor Texture Packer downloading
Refactor local-config.js tasks file into a generic "environment"
category consisting of checking if Java is installed, downloading the
runnable Texture Packer if it's not yet downloaded and copying the local
configuration template; update README accordingly.
* Prepare environment only at postinstall
Remove environment.prepare task from default build pipelines, add a
postinstall script that calls the task, using environment.js as the
gulpfile to speed it up.
* Remove "docs" tasks and types generation script
Remove tasks from docs.js as they are unlikely to do anything meaningful
nowadays. Also remove the buildTypes script as it doesn't work anymore.
A better solution will be provided in the future.
* Simplify some globs
Use additional gulp.src options instead of specifying more or complex
globs.
* Extract built-temp location to a variable
Add the src/js/built-temp directory as a new variable in config.js,
replace all existing references to built-temp with this variable.
* Unify the version source
Changes the development config to use version from package.json and
makes the production config use the same utility function. Also removes
the version file as it's no longer needed.
* Remove some Steam references from build process
Removes files needed to publish the game on Steam and related tasks that
can be only used by the developer anyway. Only the build process is
affected, the actual game part still supports Steam integration.
* Refactor/add packaging tasks
Adds new Gulp tasks to create a distributable package of the game. A
task for macOS is not provided because signing needs to be figured out
first. Package creation tasks are also aliased in package.json for
future usage in external tools or CI. Aside from that, alternative
methods of downloading the libGDX Texture Packer are dropped.
