fix(server): Fix link when external IP is IPv6 (#335)

The external IP module can return an IPv6 address, in which case the
method to append a port is to wrap it in square brackets before
appending the ":%d" port string.

Unfortunately Go's IP module does not have a great way to determine
whether an address is an IPv6 address, so fall back to counting the
number of colons in the result as suggested in
https://stackoverflow.com/a/48519490.

chore(go): require go 1.18 (#322)

* fix: require go 1.18

Fixes "predeclared any requires go1.18 or later (-lang was set to go1.16; check go.mod)"

* Updated go to 1.18 in go.sum
* Ran go mod tidy

* docs(README): update required Go version

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Co-authored-by: Claudio d'Angelis <claudiodangelis@gmail.com>

style(all): run "go fmt"

fix(zip): delete temporary file after transferring it (#304)

* Fixing deleting temporary files

* style(util):

* chore(deps): go mod tidy

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Co-authored-by: Claudio d'Angelis <claudiodangelis@gmail.com>

Use correct permissions when creating config directory (#269)

Implement --bind parameter (#266)

Do not set cookies when keep-alive is true (#231)

Disable submit button after start transferring (#212)

Co-authored-by: Vincent Lau <vincent@mobile.hkcoldtea.com>

Address golangci-lint warnings in source code

Extract filename base from multipart