Add alternate Display for concise matrix printing

Add format option for concise printing of matrices
as semicolon-delimited rows. e.g. println!("{:#}", matrix);

src/base/matrix.rs

@@ -1893,6 +1893,7 @@ macro_rules! impl_fmt {
             S: RawStorage<T, R, C>,
         {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                if !f.alternate() { // pretty print in 2D layout
                     #[cfg(feature = "std")]
                     fn val_width<T: Scalar + $trait>(val: &T, f: &mut fmt::Formatter<'_>) -> usize {
                         match f.precision() {
@@ -1924,7 +1925,7 @@ macro_rules! impl_fmt {
 
                     let max_length_with_space = max_length + 1;
 
-                writeln!(f)?;
+                    writeln!(f)?; // leading newline to ensure no offset from previous prints
                     writeln!(
                         f,
                         "  ┌ {:>width$} ┐",
@@ -1948,13 +1949,36 @@ macro_rules! impl_fmt {
                         writeln!(f, " │")?;
                     }
 
-                writeln!(
+                    write!(
                         f,
                         "  └ {:>width$} ┘",
                         "",
                         width = max_length_with_space * ncols - 1
-                )?;
+                    )
-                writeln!(f)
+                } else { // print on single line with semicolon-delimited rows and comma-delimited columns
+                    let (nrows, ncols) = self.shape();
+                    write!(f, "[")?;
+                    for row in 0..nrows {
+                        for col in 0..ncols {
+                            if col != 0 {
+                                write!(f, ", ")?;
+                            }
+                            match f.precision() {
+                                Some(precision) => write!(
+                                    f,
+                                    $fmt_str_with_precision,
+                                    (*self)[(row, col)],
+                                    precision
+                                )?,
+                                None => write!(f, $fmt_str_without_precision, (*self)[(row, col)])?,
+                            }
+                        }
+                        if row != nrows - 1 {
+                            write!(f, "; ")?;
+                        }
+                    }
+                    write!(f, "]")
+                }
             }
         }
     };