Compilation terminates whith unknown flags.

[TheGrandmother]

Compilation now fails when unknown flags are provided.
Ex:
encorec -blah test.enc
outputs
Unknown flag bla. Use -help to se avaliable flags.

A -help flag is available that outputs:

Welcome to the Encore compiler!
Usage: encorec [flags] file

Flags:
  -c           Keep intermediate C-files
  -tc          Typecheck only (don't produce an executable)
  -o [file]    Specify output file
  -run         Run the program and remove the executable
  -clang       Use clang to build the executable (default)
  -AST         Output the parsed AST as text to foo.AST
  -TypedAST    Output the typechecked AST as text to foo.TAST
  -nogc        Disables the garbage collection of passive objects.
  -help        Print this message and exit.
  -I p1:p2:... Directories in which to look for modules.

[EliasC]

se -> see

[EliasC]

I like this! Happy to merge!