Feature request: specify projectfile on the command line instead of "khafile.js"

[sh-dave]

Hi Robert,

while fiddling about with --from and --to i thought it would be nice to be able to specify the project file on the command line instead of having a hardcoded "khafile.js". If i take the example from #23, i have

@node Kha/make --target flash --from src/spriter/example-kha-g2 --to build/example-kha-g2
@node Kha/make --target flash --from src/spriter/example-kha-g4 --to build/example-kha-g4

What i'd like to do is something like ...

@node Kha/make --target flash --projectfile example-kha-g2.js --to build/example-kha-g2
@node Kha/make --target flash --projectfile example-kha-g4.js --to build/example-kha-g4

... so i don't have to keep the project files in diffrent subdirs.