Bug #6, Make SVG logo and colour styles customizable [LACE]

* Optional: wordpress/wp-config.php -- define(WP_EVIDENCE_HUB_SVG_STYLE)
* Optional: WP_EVIDENCE_HUB_SVG_LOGO ...
* Or, add these keys to the `wp_options` DB table
Bug #7, Add <title> and meta-data to SVG logos - accessibility etc. [LACE]

* Insipired by: https://openclipart.org/detail/201957/lenin-by-worker-201957
Bug #8, Add message for missing map/chart in Internet Explorer/ MSIE 7/8 [LACE]

* Partial fix.
Bug #8, Add message for missing map/chart in Internet Explorer/ MSIE8 [LACE]

* Add missing "Loading..." message etc. to shortcode PHP
Bug #9, Add debug output for the shortcode cribsheet [LACE]
Bug #9, Follow-up - add debug output for the shortcode cribsheet [LACE]
Bug #11, Reduce number of JS errors in MSIE 8, plus [LACE]

* Document Javascript globals..
Merge pull request #10 from IET-OU/iet-ou/CR6/svg-logo

iet-ou/CR6/svg-logo: Make SVG logo & colours customizable, SVG meta-data etc. [LACE]