Handle STDERR, in addition to STDOUT

This patch overhauls the reading and reciting of verses, such that the
redirection of STDERR (in addition to STDOUT, which was already a
feature), is now possible.

Removed the 'stdout' argument from recite(), since it is no longer
needed with how incantations function.

A verse's couplet indicator is now a u8, instead of a bool, with certain
values corresponding to types of couplets, for instance:

  ls | grep Ca | lolcat
  ^    ^         ^
  |    |         2: right side of a couplet
  |    3: both sides of a couplet
  1: left side of a couplet

Incantions are no longer hanlded in rune.rs, and the task macros have
been removed. Now, a verse incants itself, matching on its own meter to
determine how to handle the next verse.

The following runes were added to help with handling STDERR:
  Write2 -> 2>
  WriteAll -> &>
  Addendum2 -> 2>>
  AddendumAll -> &>>

The 'io' field in verse was changed from an Option<Rune>, to an array of
Runes, since a single verse might have multiple IO operations.

The following fields were added to Verse, to assist with handling
STDERR:
  ip -> List of filenames to read into STDIN
  op -> List of filenames to send STDOUT to
  ep -> List of filenames to send STDERR to

Keep track of channels when reading a poem. Channels are relating to IO
operations. If channel is None, words get pushed to the verse's primary
stanza (i.e. the verb or the clause). If a channel is selected, words
are pushed to one of the aforementioned new fields in Verse.
  Read -> ip
  Write/Addedum -> op
  Write2/Addedum2 -> ep
  WriteAll/AddendumAll -> op and ep

2 files changed, 2 insertions, 4 deletions

diff --git a/src/poem/anthology/alias.rs b/src/poem/anthology/alias.rs
index 511bd3a..45ee7f2 100644
--- a/src/poem/anthology/alias.rs
+++ b/src/poem/anthology/alias.rs
@@ -40,7 +40,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, aliases: &mut HashMap<String, St
                 lines.push(line);
             }
 
-            if verse.couplet {
+            if verse.couplet > 0 {
                 *out = format!("{}\n", lines.join("\n")).as_bytes().to_vec();
             } else {
                 println!("{}", lines.join("\n"));
diff --git a/src/poem/anthology/source.rs b/src/poem/anthology/source.rs
index 43d6204..3c81110 100644
--- a/src/poem/anthology/source.rs
+++ b/src/poem/anthology/source.rs
@@ -42,9 +42,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &mut Environment) -> i32 {
             }
         };
 
-        let stdout = if verse.couplet { Some(true) } else { None };
-
-        *out = match poem.recite(env, stdout) {
+        *out = match poem.recite(env) {
             Ok(out) => out,
             Err(e) => {
                 eprintln!("dwvsh: {}", e.to_string().to_lowercase());