* automake.in ($IGNORE_PATTERN): Improve for multi-line matches.

* automake.in ($IGNORE_PATTERN): Improve for multi-line matches.
($RULE_PATTERN): Use that from `&make_paragraphs'.
($MACRO_PATTERN): Just catch the name of a macro.
($BOGUS_MACRO_PATTERN): Remove.
($ASSIGNMENT_PATTERN): New.
(&file_contents_internal, &make_paragraphs): Adjust.
(&macro_define): Catch bad macro names.
(&cond_stack_endif): Better error message.
(&file_contents_internal): Don't remove backslashes in variable
values.
(&macro_define): Do it for `+=' user variables.
(&define_standard_variables): Use `undef' instead of a dummy
variable.
(&make_paragraph): Be sure not to chop the trail of hash only
lines: adjust the `##' regexp.
(&rule_define): Fix a bug: don't read $1 but $target.
* tests/condincl.test: Strengthen.