Add new npm / glup tasks: clone:default_plugins, build:dev_plugins, watch:plugins

[Raruto]

Supersedes: #301 and #262

---

What's changes:

1. Add new task gulp clone:default_plugins,

   in order to make sure that core client plugins are there before starting develop:

   • [submodule "src/plugins/qplotly"] <-- https://github.com/g3w-suite/g3w-client-plugin-qplotly.git
   • [submodule "src/plugins/openrouteservice"] <-- https://github.com/g3w-suite/g3w-client-plugin-openrouteservice.git
   • [submodule "src/plugins/qtimeseries"] <-- https://github.com/g3w-suite/g3w-client-plugin-qtimeseries.git
   • [submodule "src/plugins/editing"] <-- https://github.com/g3w-suite/g3w-client-plugin-editing.git

2. Add new task gulp build:dev_plugins,

   in order to maker sure that core and custom client bundles are up-to-date before starting the npm run dev server
   (NB: for performance reasons this script just build all plugins once, for watching them all see next point)

3. Add new script npm run watch:plugins,

   in order to avoid performing the gulp watch task on each plugin located in the local src/plugins/* directory

4. Update README.md plugin development instructions

   How to develop

   You can start the built-in development servers by using the following:

   npm run docker:up      # backend server (g3w-admin)
   npm run dev            # frontend server (g3w-client)
   + npm run watch:plugins  # watch built-in plugins + any custom plugin (eg. base, eleprofile, sidebar)

5. Remove useful gulp tasks

   definitely deprecated (and undocumented), the following tasks crash if run manually because their dependent tasks were never implemented:

   • gulp.task('g3w-admin-client:static', ['build:static']);
   • gulp.task('g3w-admin-client:template', ['build:templates']);
   • gulp.task('g3w-admin:static', ['build:static']);
   • gulp.task('g3w-admin:templates', ['build:templates']);

Advantages of this type of solution

1. no headaches with git submodules yet which would require additional documentation on how to clone and update submodules (ref: Include default client plugins (editing, qplotly, qtimeseries) as git submodules #301)
2. starts sort of automating the import of core plugins in anticipation of converting them to npm modules (ref: Replace assets vendors folder with npm packages #290)

Drawbacks

1. The following files are not yet generated automatically (to do this you still need to manually run the build:plugins task):

    src/plugins/editing/plugin.js
    src/plugins/qplotly/plugin.js
    src/plugins/qtimeseries/plugin.js
   

2. The version of the cloned repositories is not fixed to a specific release (ie. to a specific branch or commit), so an unsuspecting user could clone a version of the client plugins not immediately compatible with the current version of g3w-client

3. each developer has to worry about keeping various plugin repositories up-to-date locally

[volterra79]

@Raruto it could be useful add a way here:

g3w-client/gulpfile.js

Line 439 in 71e12e2

'clone:default_plugins',

to add a task to use plugin in development too

[Raruto]

@volterra79 are we ready to merge this?, otherwise we will never test it enough before the next release..

[volterra79]

@Raruto let's do it