[lex.ppnumber] Reorder grammar rule to make the similarities and

differences between the digit separator and non-digit-separator
productions more obvious.

Author: zygoloid

source/grammar.tex

@@ -145,9 +145,9 @@
     digit\br
     \terminal{.} digit\br
     pp-number digit\br
+    pp-number identifier-nondigit\br
     pp-number \terminal{'} digit\br
     pp-number \terminal{'} nondigit\br
-    pp-number identifier-nondigit\br
     pp-number \terminal{e} sign\br
     pp-number \terminal{E} sign\br
     pp-number \terminal{.}

source/lex.tex

@@ -530,9 +530,9 @@
     digit\br
     \terminal{.} digit\br
     pp-number digit\br
+    pp-number identifier-nondigit\br
     pp-number \terminal{'} digit\br
     pp-number \terminal{'} nondigit\br
-    pp-number identifier-nondigit\br
     pp-number \terminal{e} sign\br
     pp-number \terminal{E} sign\br
     pp-number \terminal{.}