Optimize template replacement speed

[0fv]

1. fix clone() set parent method
2. optimize expandPlaceholders(xnode *xmlNode) ,reduce loop time
3. optimize replaceSingleParams(xnode *xmlNode, triggerParamOnly bool),reduce loop time

before:

goos: linux
goarch: amd64
pkg: github.com/bobiverse/docxplate
cpu: Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz
BenchmarkLists100-6     1000000000               0.4386 ns/op
BenchmarkLists200-6            1        1693713947 ns/op
BenchmarkLists400-6            1        6552133541 ns/op
BenchmarkLists1000-6           1        40482876671 ns/op
PASS
ok      github.com/bobiverse/docxplate  60.426s

after:

goos: linux
goarch: amd64
pkg: github.com/bobiverse/docxplate
cpu: Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz
BenchmarkLists100-6     1000000000               0.01451 ns/op
BenchmarkLists200-6     1000000000               0.02569 ns/op
BenchmarkLists400-6     1000000000               0.04924 ns/op
BenchmarkLists1000-6    1000000000               0.1187 ns/op
PASS
ok      github.com/bobiverse/docxplate  3.301s

[bobiverse]

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