Rewrote build script, improved packaging

- Renamed :packageWindows to :packageNsis
- ImageMagick now required for :packageNsis
- Packaging output is now in build/packages
- Rewrote build script
  - Packaging logic and LWJGL dependencies now in separate files
  - Packaging logic now implemented with Gradle, not Bash scripts
    - Cross-platform?
- Added :packageZip
  - Universal ZIP with start scripts
- Changed version detection logic
  - Tags of ancestor commits are now considered
  - Only tags with format vMAJOR.MINOR.PATCH[-SUFFIX] are considered
  - If the tag's commit isn't HEAD, PATCH is incremented
  - When version detection fails, dummy version is 999.0.0-<buildID or date>
- LWJGL target platforms can be overridden with forceTargets project property

build_logic/packaging/deb/script.gradle

@@ -0,0 +1,38 @@
+task packageDeb_processResources(type: Copy) {
+	dependsOn resolveVersion
+	dependsOn preparePackaging
+
+	from 'src/packaging/deb'
+	
+	filesMatching('DEBIAN/control') {
+		expand(version: { -> project.version})
+	}
+	
+	into 'build/tmp/packaging/workingDir'
+}
+
+task packageDeb_configure() {
+	preparePackaging.mustRunAfter packageDeb_configure
+
+	doLast {
+		tasks.preparePackaging.ext.buildDest = '/usr/share/progressia'
+		tasks.preparePackaging.ext.mode = 'copy'
+	}
+}
+
+task packageDeb(type: Exec) {
+	description 'Builds the project and creates a Debian package.'
+	group 'Progressia'
+	
+	dependsOn packageDeb_configure
+	dependsOn requestLinuxDependencies
+	dependsOn build
+	dependsOn preparePackaging
+	
+	dependsOn packageDeb_processResources
+	
+	executable 'dpkg-deb'
+	args '--root-owner-group'
+	args '--build', 'build/tmp/packaging/workingDir'
+	args 'build/packages'
+}