When PUGIXML_STRING_VIEW define is set and C++17 is available, add std::string_view support to a few functions. In the future, string view support will be enabled without the need for an extra define, but for now the support is opt-in to reduce compatibility risks.
PR is based on initial contribution by @brandl-muc.
Here we also test what happens when text gets assigned to an empty
string after initially being non-empty, to make sure this is not
different from the initial state.
We had a few places in test code and library source where we used an
implicit float->double cast; while it should preserve the value exactly,
gcc/clang implement this warning to make sure uses of double are intentional.
This change also adds the warning to Makefile to make sure we don't
regress on this warning.
Fixes#243.
When using format_raw the space in the empty tag (<node />) is the only
character that does not have to be there; so format_raw almost results in
a minimal XML but not quite.
It's pretty unlikely that this is crucial for any users - the formatting
change should be benign, and it's better to improve format_raw than to add
yet another flag.
Fixes#87.
