Allow text file preview for all UTF-8 encoded files

[eulores]

A number of PDF files converted into text (mutool convert...) still have few innocuous control characters (typically 0x0c replacing a page break). But these bug Broot into displaying them as hex dumps.

Please consider this patch below for Broot to be more lenient and accept all UTF-8 encoded files, simply by replacing control characters with space (or an empty string).

Binary files are unaffected by this patch, as they get rejected earlier by not being UTF-8 compliant.

diff --git a/src/syntactic/syntactic_view.rs b/src/syntactic/syntactic_view.rs
             self.total_lines_count += 1;
             let start = offset;
             offset += line.len();
+            line = line.replace(|ch: char| ch.is_control() && !"\t\n\r".contains(ch), " ");
-            for c in line.chars() {
-                if !is_char_printable(c) {
-                    debug!("unprintable char: {:?}", c);
-                    return Err(ProgramError::UnprintableFile);
-                }
-            }