e-xml: Only export public API functions in shared library

Don't clutter namespace.

objdump --dynamic-syms Release/libe-xml.so | grep " g    " | wc -l
Before: 262
After: 27
e-xml: Fix mismatched delete / new[]
e-xml: Add include guards to header files
e-xml: Add include guards to header files
e-xml: Add C api
e-xml: Add example program that uses C bindings
Merge branch 'pr-export-api-only-2'
Merge branch 'pr-mismatched-delete-2'
Merge branch 'pr-include-guards-2'
Merge branch 'pr-xml-c-api-2'

Conflicts:
	src/e-xml/Makefile