go.mod: all modules updated; tidy

go.mod: cdk v0.5.22; tidy

README.md: content updates; correct install command

go.mod: cdk v0.5.19; tidy

go.mod: cdk v0.5.18; tidy

go.mod: cdk v0.5.17; all modules updated; tidy

go.mod: cdk v0.5.16; all modules updated; tidy

go.mod: cdk v0.5.15; tidy

window: gofmt code cosmetic changes

go.mod: cdk v0.5.14 (display startup error handling update); tidy