fix(columns): Fix columns generation and date/position computations

This add unit tests for gantt position/date computation.

This also fix many possible issues due to invalid computations and bad generation of previous/next invisible columns.

It also adds an options object into gantt object to better support default values of gantt options (attributes).
feat(labels): Add header option to labels plugin

Set header attribute to customize label in the upper-left corner of the gantt.
chore(release): Release v1.0.0-rc8
fix(moveable): Task continues to scroll when moved to another row during scrolling

When moving a task to a new row while scrolling - the scrolling doesn't stop. This is because a new scope is generated when the task is moved to a new row but the old scope is still in the move-scroll-... cycle. The fix will set a flag when the scope is destroyed and the scroll cycle will stop if this flag is set.
fix(side): Show/Hide side section leads to display issues with body part

Because of a copy & paste error (labelsBody) and usage of a wrong options value (resizer) the show/hide side section doesn't work correctly. Additionally removed some unused code + comments related to this issue.
refac(labels): Renaming of css getter function
fix(css): Gantt border is shown far to the right if content is smaller than gantt width

If the content is smaller than the gantt width the border is still displayed on the far right resulting in a ugly gap. This can only happen if columnWidth if set and the content is smaller => e.g. when the data range is small and viewScale is quarter/year.
fix(options): Boolean default options are not handled correctly

Boolean default options which are true are returned as undefined. Because if this an issue occurs with the side section. The side section has now a fixed defined height to simplify gantt resize calculations. Thus if no side plugin is loaded the side section should be hidden (default) otherwise its shown as empty.
test(options): Improved code coverage
fix(show-side): Fix show-side default value implementation

Close #265
docs(get-started): Add instructions to display row labels
feat(side-width): Remove side-width default value

Default side-width is now be computed on rendering, based on size of side component.

It also removes useless getSideCss() method and related ng-style binding causing layout issues.

Close #264
feat(show-side): Change show-side default value to true

It doesn't have any negative side-effect even if no side plugin is loaded.
chore(release): Release v1.0.0-rc.9
fix(layout): Fix invalid layout when maxHeight is enabled

Close #266
feat(task): Enhance template of task

This structure task template with a foreground, background and content directives. It makes the tooltip cutoff fix possible, by applying css styles to background div only.

Close #254
feat(dateRange): Hide tasks that are outside date range

Close #271
fix(data): Data property changes not applied to internal data structure. LoadData call causes short loop.

When calling loadData a short loop is created because the rowManager will change the data property which then will call loadData again. Additionally changes in the order of the data model are not reflected into the internal data structure affecting sorting by drag&drop. To prevent those and other issues loadData, removeData and clearData use now the data property. Thus the data property is the "master" of all data management and no loops are possible anymore.  Since this is not very efficient (copy data into data property and copy data to internal structure) all three functions are marked as deprecated. Either they can be removed in the future or be used as convenient functions.
chore(release): Release v1.0.0
fix(docs): Fix docs subfolders