Fix issue with converting INO to CPP and missing line number

docs/projectconf.rst

@@ -194,8 +194,8 @@ if :option:`platformio run --environment` option is not specified.
 :ref:`projectconf_pio_env_default` allows to define environments which
 should be processed by default.
 
-Multiple environments are allowed if they are separated with ``, `` (comma+space).
-For example.
+Multiple environments are allowed if they are separated with ``, ``
+(comma+space). For example.
 
 .. code-block:: ini
 

platformio/builder/tools/piomisc.py

@@ -90,7 +90,7 @@ class InoToCPPConverter(object):
         return isfile(out_file)
 
     def _join_multiline_strings(self, contents):
-        if "\\" not in contents:
+        if "\\\n" not in contents:
             return contents
         newlines = []
         linenum = 0
@@ -99,7 +99,6 @@ class InoToCPPConverter(object):
             _linenum = self._parse_preproc_line_num(line)
             if _linenum is not None:
                 linenum = _linenum
-                continue
             else:
                 linenum += 1