add <?xml> element to allow comments before <svg>; added test case fo… #16

	# Workflow for hcontours
	name: Go Build and Test
	on:
	push:
	branches: [ "main" ]
	pull_request:
	branches: [ "main" ]
	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- name: Set up Go
	uses: actions/setup-go@v4
	with:
	#go-version: '1.22'
	go-version-file: 'go.mod'
	- name: Install dependencies
	run: \|
	go get .
	go get github.com/spf13/pflag
	go get golang.org/x/exp
	- name: Build
	run: go build -v ./...
	- name: Test
	run: go test -v ./...
	# - name: Use
	# run: cd examples && ../hcontours beach.png -t 32,64,96,128,160,192,224

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