feature-request: header-files for C/C++ libs support on iOS platform

[elmasse]

The current implementation allows to define ObjectiveC headers and source files. For those plugins that are using external C/C++ libs we need a spec to copy the header files with their current folder structure and add them to HEADERS_SEARCH_PATH list inside the Xcode project.

proposal:

<header-file src="src/ios/framework/libs/include" target-dir="lib/include" framework="true" />

having framework=true and referencing a folder into a header-file element could copy the current structure and add the target-dir into the HEADER_SEARCH_PATH with a recursive mark.

Not sure about using header-file element for this, but we need a solution for this type of plugins, so I wanted to open the discussion here.