Rename configure.in -> configure.ac
Fix locating X color database on Mac OS X
Modernize configure.ac
Fix 'make regress' when current dir is not in PATH
Fix autogen.sh if . is not in the PATH
Change autogen.sh to use autoreconf

One may wish to just remove this script now...
Add missing #include <string.h>
Updated to use modern libpng interfaces
Fix (?) intent validation in dump_sRGB
Fix handling of translated keyword in iTXT chunks
Increase token_buffer size to fix support for long text blocks

This fixes handling ctgn0g04.png in the PNG test suite
Run sng_regress against the freshly compiled sng
Fix iCCP support

As per the PNG specification, the only supported compression mode is
PNG_COMPRESSION_TYPE_BASE.
Fix cHRM entry in test.sng

Without this, the validations performed by newer libpng will reject
the file due to invalid chromaticities.
Fix some #ifdef's
Disable fake iCCP in test.sng

Newer libpng versions perform sanity checks on input data, and error
out once they recognize that the fake iCCP in test.sng is bogus (it is
too short). So we comment out the iCCP block.
Remove compatibilty code for old libpng versions
Avoid warning with libpng before 1.6
Do not use PNG_INTERNAL
Fix two pedantic warnings