* when appending log field only do so by minimal amount
* move slice utils to separate package to fix import cycle, add GrowJust() and AppendJust() functions
* fix GrowJust() not returning slice of same length
* improved xslices tests
* make AppendJust() test check for slice contents, fix AppendJust() final copying behaviour
* add a +1 with field growth to try minimise allocation for log 'msg' field
* replicate issue
* update go-structr to v0.8.10 with internal linked-list fix, small tweaks to caching of interaction requests
* remove debug function
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Co-authored-by: tobi <tobi.smethurst@protonmail.com>
kim