misc/abi-check: This new script can be used (on Linux) to check ABI
compatibility between patch releases. It does everything required
in one execution (after installing the prerequisites once).
Documentation is included in the script. It may be modified for
other platforms, or ABI checking can be done manually.
README.abi-version.txt: add a chapter regarding ABI checks
misc/abi-compliance-checker.txt: update documentation on how to run
misc/abi-check. In previous versions (1.4) building was done using
configure/make. Thus this file was almost completely rewritten.
documentation/src/migration_1_4.dox: an unrelated but tiny correction.
