Add checkstyle configuration based on Google Java style

[sbesson]

Fixes #33

24ca578 adds the checkstyle plugin and the Google Java style configuration for Google Java style from https://checkstyle.org/google_style.html.
cacb96e, cd75d5c and 1a4a5e4 make amendments this configuration to:

• use the default checkstyle indentation - https://checkstyle.org/checks/misc/indentation.html
• use the default checkstyle naming conventions - https://checkstyle.org/checks/naming/index.html
• allow abbreviations with 5 consecutive capital letters e.g. XYZTC - https://checkstyle.org/checks/naming/abbreviationaswordinname.html
  1bead65 sets the severity to error so that future violations fail the Gradle build

All other commits update the omero-zarr-pixel-buffer implementation to comply with the style configuration. Most of these updates are fairly standard and should be non controversial (indentation, import ordering, camel-case style). There are a few styling rules that differ from other repositories e.g. the requirement to not have operators like || at the end of a line. Leaving reviewers to establish whether it would be preferable to relax the rules instead of fixing the code.

[kkoz]

Just a couple wording suggestions. Otherwise looks good

[chris-allan]

I'm fully supportive of the checkstyle configuration. I think my only issue with this is the construction of the commits and how/if we attempt to correctly utilize git-blame-ignore-refs.

Do you have thoughts on that already, @sbesson?

[sbesson]

Thanks @chris-allan, a .git-blame-ignore-refs should be added to the top-level of this repository to improve examination of code changes moving forward.

The the current commit organisation was made with reviewing in mind to simplify the reversal of individual rules if needed. If we all agree on the content, these could be consolidated into four commits and this branch updated (via force push) as follows:

• one commit to add the original Google checkstyle configuration and the build.gradle updates
• one commit to add our modifications (indentations)
• one commit with all the changes to the Java code to comply with the checkstyle
• one commit to exclude the previous reference via .git-blame-ignore-refs

If we'd rather not force-push, I would add all commits a5221d0 up to ff26161 to .git-blame-ignore-refs

[chris-allan]

Let's go with the force push and see how things look.

[sbesson]

Took several force pushes but the diff between the previous history and the new history with squashed commits and the .git-blame-ignore-revs addition is reviewable at https://github.com/glencoesoftware/omero-zarr-pixel-buffer/compare/9e8d92a1bfc2ece12384d9626b096ec11afea944..f683540