fix: escaped newline immediately after a char, resolves #100 (#102)

corpus/programs.txt

@@ -41,6 +41,41 @@ f=g   \
     (command_name (word))
     (word)))
 
+=============================
+escaped newline immediately after a char
+=============================
+
+echo a \
+    b
+
+echo a\
+    b
+
+echo a\
+    b\
+    c
+
+
+-----------------------------
+
+(program
+  (command
+    (command_name
+      (word))
+    (word)
+    (word))
+  (command
+    (command_name
+      (word))
+    (word)
+    (word))
+  (command
+    (command_name
+      (word))
+    (word)
+    (word)
+    (word)))
+
 =============================
 Escaped whitespace
 ============================

src/scanner.cc

@@ -172,6 +172,7 @@ struct Scanner {
       if (!(
         lexer->lookahead == 0 ||
         iswspace(lexer->lookahead) ||
+        lexer->lookahead == '\\' ||
         lexer->lookahead == '>' ||
         lexer->lookahead == '<' ||
         lexer->lookahead == ')' ||