[WIP] adopt hwk's command-line API

[gelisam]

TODO:

• [ ] fix the tests
• [ ] default to not splitting into words
• [ ] delete the now-unused homemade argument-parsing library
• [ ] delete the now-unused Spec types
• [ ] implement the missing modes (except Shell)
• [ ] update the documentation
• [x] make it clearer what the default mode is

[juhp]

It now builds back to lts-10.7.

[juhp]

The tests are now passing but likely still missing some mode handling.

[juhp]

Hmm, hawk '2+2' also fails locally for me :-(

But hawk -e '2+2' works.

[gelisam]

Hmm, hawk '2+2' also fails locally for me :-(

But hawk -e '2+2' works.

Looks like the default behaviour when no flags are specified switched from printing a value to splitting lines into words and applying a transformation on each of them:

> $ echo "hello world" | hawk 'reverse'
world hello

[juhp]

processSpec (src/System/Console/Hawk.hs) still needs to handle each HawkMode.