* include/wget/wget.h: Add function declarations
* libwget/plugin.c: Add virtual functions
* src/plugin.c: Add implementation
* src/wget_plugin.h: Likewise
* src/wget.c: Add code that calls the implementation
* src/wget_job.h: Add a variable to store 'accept' action
* tests/Makefile.am: Add libpluginapi.la
* tests/test-plugin-dummy.c: Add a test plugin for testing
* tests/test-plugin.c: Add tests
Plugin API for intercepting URLs has been implemented as per
specifications at https://gitlab.com/akash_rawal/wget2/wikis/Stage-2
* include/wget/wget.h: Add API for command line option forwarding
* libwget/plugin.c: Likewise
* libwget/test_linking: Add function from libwget/plugin.c
* src/dl.c: Remove unused dl_search1() and dl_list1(),
use wget_vector_t for pointer arrays
* src/wget_dl.h: Likewise
* src/plugin.c: Implement option forwarding
* src/wget_plugin.h: Likewise
* src/options.c: Add options '--plugin-opt=', '--plugin-help'
* unit-tests/test-dl.c: Use dl_list() instead of dl_list1()
* tests/Makefile.am: Add test plugins pluginoption, pluginfaulty1,
pluginfaulty2
* tests/test-plugin-dummy.c: Implement additional test plugins
* tests/test-plugin.c: Extend tests for testing option processing
Command line option forwarding has been implemented as per
specifications at https://gitlab.com/akash_rawal/wget2/wikis/Stage-1
Several style issues were also fixed (Thanks Ander Juaristi)
* configure.ac: Add configure time tests for plugin support backend.
* include/wget/wget.h: Add basic plugin API
* libwget/Makefile.am: Add new file plugin.c to libwget.la
* libwget/plugin.c: Add plugin API functions (new file)
* src/Makefile.am: Add new files dl.c, wget_dl.h, plugin.c, wget_plugin.h
to wget2
* src/dl.c: Add abstraction for dynamic loading of object files
* src/wget_dl.h: Likewise
* src/plugin.c: Add implementation for loading plugins
* src/wget_plugin.h: likewise
* src/options.c: Add options `--plugin=`, `--local-plugin=`,
`--plugin-dirs=`, `--list-plugins`
* src/wget.c: Add function calls to initialize and finalize plugin
support system
* unit-tests/Makefile.am: Add test-dl, libalpha.la, and libbeta.la
* unit-tests/test-dl.c: Add unit test for src/dl.c
* unit-tests/test-dl-dummy.c: Likewise
* tests/Makefile.am: Add test-plugin, libpluginname.la, and
libpluginexit.la
* tests/test-plugin.c: Add tests for plugin support
* tests/test-plugin-dummy.c: Likewise
* libwget/test-linking.c: Fix warnings with --enable-manywarnings
* unit-tests/test.c: likewise
Plugin loading mechanism has been implemented as per specifications
at https://gitlab.com/akash_rawal/wget2/wikis/Stage-0
