Java required when making multiple targets

[JennaSys]

When just making (no --build option) for multiple targets, the compiler tries to load existing target code and ends up running the closure compiler (for minification) jar which requires Java to be installed.

Transcrypt/transcrypt/modules/org/transcrypt/compiler.py

Lines 233 to 241 in 32b216b

	if not javascriptDigest:
	minify.run (
	self.program.targetDir,
	self.targetName,
	self.prettyTargetName,
	prettify = True,
	)
	self.prettyTargetCode = open (self.prettyTargetPath, 'r') .read ()
	javascriptDigest = utils.digestJavascript (self.prettyTargetCode, self.program.symbols, True, False) # Prettified, so doesn't start with '/'!

There should be a way to avoid having Java installed when the target does not actually exist yet.