ensure we do not query layers with no active styles
ctrans: add getter for offsets
use std::fabs not fabs
Add visual test of multiple chained image filters
enable new test
add support for seamless blurring - closes #1478
tests: add visual test using multiple blurs
tests: be more explicit about png encoding comparison formats
default to hextree encoding for 'png' format + png options cleanup
webp: cleanup option handling
webp: use WebPConfig instead of custom options struct
expose all remaining webp encoding options except for 'show_compression' - refs #1964
Add ticket reference for png format default change
update webp defaults to use WebPConfigInit
Add wiki page link
handle conditional compile of webp options not available before webp-v0.1.99
tests: wrap all web tests in try catch to avoid failures with older versions
merge with branch 2.3.x