[WIP] rclcpp design

[Theosakamg]

Link to https://github.com/esteve/ros2_java/pull/8

[esteve]

@Theosakamg @elehuitouze thanks for your contributions, they are great!

As I asked @Theosakamg on his ros2_java pull request (https://github.com/esteve/ros2_java/pull/8#issuecomment-257613110 and https://github.com/esteve/ros2_java/pull/8#issuecomment-260190111), I would really prefer if you created separate pull requests for each improvement, I can't merge this pull request as is.

One particular thing is that this pull request replaces the Gradle plugin with your own. It'd be great if you submitted any improvements to the Gradle plugin I created (https://github.com/esteve/ament_gradle_plugin), otherwise it's going to confuse users as to which Gradle plugin to use. Moreover, what features were missing in my Gradle plugin? I had a quick look at yours and it does not work with Android, and the support for Eclipse in your plugin is broken. If you want to add support for Eclipse, you only need to modify the build.gradle file in a Gradle project to add apply plugin: 'eclipse' (https://docs.gradle.org/current/userguide/eclipse_plugin.html#sec:eclipse_usage), so I don't fully understand why you built that into your Gradle plugin.

[esteve]

@Theosakamg @elehuitouze so, any update? No response from you guys since I ask you to split it into concrete pull requests, so I'm thinking of closing this pull request in the following days if I don't hear from you.

[Theosakamg]

@esteve Sorry for delay. the PR is WIP.