fix order of template arguments to fix overload resolution

do not define quantities per retag or rescale to prevent overloading …

…failing due to non-deducable contexts

updated changelog

merge branch 'unit_strings' into 'main'

updated change log

Merge pull request #12 from gitsbi/tagget-unit-comparison

do not allow quantities with different tags to be compared

fixed/extended changes.txt

Merge pull request #10 from gitsbi/fp_comparisons

major redesign of floating point comparison

added an untag function to simplify tag_cast'ing to an untagged type

added untag to simplify tag_cast'ing to no_tag