release v2021.1.5

rollup of changes already published to CPAN

v475.1.20

libclearpress-perl (475.1.20) stable; urgency=low

• Significant refactoring of HTTP response headers and error-serving

v473.0.2

libclearpress-perl (473.0.2) stable; urgency=low

• Added base64 filter: [% string | base64 %] - useful for inline image data
• Quietened down DBI DESTROY/disconnect warnings
• Added basic SVG response and content-type support
• JSON response content-type changed from application/javascript to application/json