* Reduced memory for attribute and body objects, see `XML_NEW_DIFFERENTIATE` compile-time option.
* Optimized cbuf handling in parsing and xml2cbuf functions.
* Optimized xml scanner to read strings rather than single chars
* Optimized xml_merge for the case of disjunct trees.
* If fails, exit with error message, eg: `Yang error: Sanity check failed: LIST vsDataContainer lacks key statement which MUST be present (See RFC 7950 Sec 7.8.2)`
* Can be disabled by setting `CLICON_CLICON_YANG_LIST_CHECK` to `false`
threshold of quadratic and linear growth of CLIgen buffers (cbuf:s)
* Memory footprint
* Do not autopopulate namespace cache, instead use on-demand, see `xml2ns()`.
* Set CBUF start level to 256 (`CLICON_CLI_BUF_START` option)
* Reduced xml child vector default size from 4 to 1 with quadratic growoth to 64K then linear
