This adds a simple script which parses Kconfig files using Kconfiglib
and emits ReST document with the list of all options. For each option
a link target is generated, to make it possible to link to any Kconfig
option from the rest of the documentation.
Since Kconfiglib is not on PyPI, the latest version (45f87b9d) is
bundled into the docs directory.
For config-only components, component.mk should now contain "COMPONENT_CONFIG_ONLY := 1"
Also refactored some of the generation of linker paths, library list. This required cleaning up the way the bootloader
project works, it's now mostly independent from the parent.
Each COMPONENT_DIRS directory can now either be a component directory, or a parent directory containing component
subdirectories.
When searching for components, skip any directory which doesn't have component.mk, Kconfig.projbuild, or
Makefile.projbuild in it. This helps with debugging, list-components output, etc.
