YAML parameter parser (#235)

* Implement a basic YAML based parameter parser for ros2 nodes

* Add README file

* Fix the issues after moving from rcutils_yaml_param_parser to rcl_yaml_param_parser

  - rename folders from rcutils_yaml_param_parser to rcl_yaml_param_parser
  - rename project, header guards and include statements from rcutils_yaml_param_parser to rcl_yaml_param_parser
  - move type declaration in separat file and namespace new structures
  - Fix the code review comments from Mikael

* Few minor changes

   - Changed "params" string to "ros__parameters"
   - Add -Wall, -Wextra and -Wpedantic falgs
   - Fix the compile warning with the new flags

* Fix the changes made in the design of C structure

  - Remove the node_namespaces entry in rcl_params_t
  - Change the type of num_nodes and num_params to size_t

* depend on libyaml_vendor (#236)

* Fix cmake setting standard(C and C++) and add byte_array in C struct

*   Remove C11 so that it defaults to C99

* [rcl_yaml_param_parser] fix export symbols (#237)

* add visibility macros

* remove unused macro

* Support for multi level node and parameter name spaces

* Additional fixes and cleanups

  - Support for string namespace seperator
  - Provide parameter structure init function API
  - name cleanups

* off by 1

* Call yaml_parser_delete()

* fclose(yaml_file)

* free() allocated paths

* Call yaml_event_delete()

* completely deallcoate string array

* Few cleanup changes

  - Add install command into CMakelists.txt
  - Replace one of the zero_allocate with reallocate
  - Pass allocator state
  - Fix int32_t -> rcl_ret_t return value

* Don't include unistd.h

* Use size_t for array indices

* Just pass the allocator in the init function

rcl_yaml_param_parser/CMakeLists.txt

@@ -0,0 +1,62 @@
+cmake_minimum_required(VERSION 3.5)
+
+project(rcl_yaml_param_parser)
+
+find_package(ament_cmake_ros REQUIRED)
+find_package(rcutils REQUIRED)
+find_package(rcl REQUIRED)
+find_package(libyaml_vendor REQUIRED)
+find_package(yaml REQUIRED)
+
+# Default to C++14
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 14)
+endif()
+
+if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID MATCHES "Clang")
+  add_compile_options(-Wall -Wextra -Wpedantic)
+endif()
+
+include_directories(include ${yaml_INCLUDE_DIRS} ${rcutils_INCLUDE_DIRS} ${rcl_INCLUDE_DIRS})
+
+set(rcl_yaml_parser_sources
+  src/parser.c
+)
+
+add_library(
+  ${PROJECT_NAME}
+  ${rcl_yaml_parser_sources})
+ament_target_dependencies(${PROJECT_NAME} "yaml" "rcutils" "rcl")
+
+# Causes the visibility macros to use dllexport rather than dllimport,
+# which is appropriate when building the dll but not consuming it.
+target_compile_definitions(${PROJECT_NAME} PRIVATE "RCL_YAML_PARAM_PARSER_BUILDING_DLL")
+
+install(TARGETS ${PROJECT_NAME}
+  ARCHIVE DESTINATION lib
+  LIBRARY DESTINATION lib
+  RUNTIME DESTINATION bin)
+
+if(BUILD_TESTING)
+  find_package(ament_cmake_gtest REQUIRED)
+  find_package(ament_lint_auto REQUIRED)
+  ament_lint_auto_find_test_dependencies()
+
+  # Gtests
+  ament_add_gtest(test_parse_yaml
+    test/test_parse_yaml.cpp
+  )
+  if(TARGET test_parse_yaml)
+    target_link_libraries(test_parse_yaml ${PROJECT_NAME})
+  endif()
+
+endif()
+
+ament_export_dependencies(ament_cmake)
+ament_export_include_directories(include)
+install(
+  DIRECTORY include/
+  DESTINATION include
+)
+ament_export_libraries(${PROJECT_NAME})
+ament_package()