Removed unused code.
Fix for #1215 - each layer now has its own 'DetailsTabPanel' (rather than being shared).
Style panel initialised with layer.
InfoTab is now initialised with layer.
Renamed 'initWithSelectedLayer' to 'initWithLayer' for consistency.
SubsetTab and FilterGroupPanel are now initialised with a layer.
NcWmsPanel is now initialised with a layer.
Deleted unecessary show/hide code in DetailsPanel.
Removed remnants of 'handleLayer' related code.
InfoPanel now extends Ext.form.Label, since it is just some HTML (and calls like `this.body.update` were causing issues when the panel had now been rendered).
Removed unecessary (and buggy) id.
Removed some no longer necessary `doLayout()` calls.
Merge pull request #1271 from aodn/issue_1215

Issue 1215