Release notes: Warn that BibTeX errors cause compilation failure
lib/Makefile.am: Add missing images
lib/Makefile.am: Fix
configure.ac: back to development version
Initialize variable to fix Counter 0 problem

Fixes: #9070
Remove obsolete formats from file dialog

It is confusing for the users to see the formats 1.3--1.6 in the file-open
dialog and not the 2.0 format. The exotic extensions were only used when
e.g., LyX 1.6.x exported to LyX 1.5.x format.
Intro.lyx: change a sentence to avoid misunderstandings

- as reported today on the lyx-docs list