Macroprocessor: fix newlines in output when under Windows and input uses CR+LF convention

If the input .mod file uses CR+LF convention, and if the user is under Windows,
then the output of the macroprocessor (as given by the “savemacro” option) had
incorrect end of lines: those would be CR+CR+LF.

The reason is that some TextNode(s) internally created by the macroprocessor
would themselves contain CR+LF sequences, which would then be transformed into
CR+CR+LF in the output (because MinGW transforms LF into CR+LF in output
streams).

The fix consists in changing the nature of the EOL token: the parsed text is no
longer attached to it, so that the Bison file now systematically turns it into
a LF inside TextNode(s).

Closes: #80