LGTM.com-inspired changes:

- Fix: Ensure all apostrophes are escaped for `toXml` utility
- Fix: Avoid error if `URL` is not defined
- Fix (jPicker): Precision argument had not been passed in previously
- Fix (Star extension): Minor: Avoid erring if `inradius` is `NaN`
- Refactoring: Avoid passing unused arguments, setting unused variables,
  and making unnecessary checks; avoid useless call to `createSVGMatrix`
- Linting (LGTM): Add `lgtm.yml` file (still some remaining items flagged
  but hoping for in-code flagging)
- Docs: Contributing file

docs/Contributing.md

@@ -0,0 +1,15 @@
+# Contributing
+
+1. Prefix every change in the commit with one of the following types (and
+  sort into this order):
+  - `Security fix: `
+  - `Breaking change: `
+  - `Fix: `
+  - `Fix (<component>): ` Component may be an extension, locale, etc.
+  - `Enhancement: `
+  - `Refactoring: `
+  - `Linting (<type>):` - Linting by type, e.g., "ESLint"
+  - `Docs: `
+  - `Update: ` - e.g., if updating a bundled library
+  - `Build: `
+  - `npm` - Updates to dependencies, npm version, etc.