Correct base template name

The base template name used in $loader1 and $loader2 is actually
"base.html", not "base.twig".
Revert "bug #1535 fixed negative number lexing (fabpot)"

This reverts commit 7bda3b61037fdfcae159b490053cfb3d0c5bc43f, reversing
changes made to c86e621e09ffbfe9f7d082476fc01d32b1f759fb.

Conflicts:
	CHANGELOG
minor #1546 [doc] [api.rst] Correct base template name (fabschurt)

This PR was merged into the 1.16-dev branch.

Discussion
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[doc] [api.rst] Correct base template name

The base template name used in $loader1 and $loader2 is actually "base.html", not "base.twig".

Commits
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882f44b Correct base template name
Revert "bug #1470 Fixed "in" operator (hason)"

This reverts commit 5b172b5175e5985d144cc59985627d8820d32260, reversing
changes made to 0d0cdba3bb239efa20a0bd0c4a890a41d529d672.
updated CHANGELOG