zmakebas converts a Spectrum Basic program written as a text file into
an actual speccy Basic file (as a .TAP file, or optionally a raw
headerless file).

Using zmakebas rather than (say) writing the Basic in an emulator
means you can write using a nicer editor, and can use tools which work
on text files, etc. Also, with the `-l` option you can write without
line numbers, using labels in their place where necessary.
