Strip carriage returns (^M) when filtering emails

Presumably some email servers will transform newlines into carriage
return new lines to better support windows users. I can't prove this but
that's the best explanation I have for my hosted email provider
(fastmail).

Without this patch, I was seeing annoying `^M`s at the end of every
filtered line.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>

filters/hldiff

@@ -10,6 +10,9 @@ BEGIN {
 }
 {
 	if (hit_diff == 0) {
+		# Strip carriage returns from line
+		gsub(/\r/, "", $0)
+
 		if ($0 ~ /^diff /) {
 			hit_diff = 1;
 			print bright $0 reset
@@ -23,6 +26,9 @@ BEGIN {
 			print $0
 		}
 	} else {
+		# Strip carriage returns from line
+		gsub(/\r/, "", $0)
+
 		if ($0 ~ /^-/) {
 			print red $0 reset
 		} else if ($0 ~ /^\+/) {

filters/plaintext

@@ -5,6 +5,9 @@ BEGIN {
 	reset = "\x1B[0m"
 }
 {
+	# Strip carriage returns from line
+	gsub(/\r/, "", $0)
+
 	if ($0 ~ /^On .*, .* wrote:/ || $0 ~ /^>+/) {
 		print dim cyan $0 reset
 	} else {