Implement a class to store and retrieve the semantic version number

[MatthewKosloski]

Currently, we're storing the semantic version number of the compiler as a string (see here). To provide more semantics and validation, we should implement a Version class (similar to that used in TypeScript, here) that can store the three dot-separated numeric identifiers we use to describe the compiler version numbers.

Should use the following regex to validate against (taken from the node-semver package here):

(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)

Tentative acceptance criteria:

• Should be able to construct new versions by passing in a major number, minor number, patch number, or all three (if one is not provided, then default to zero).
• Should provide accessor methods to retrieve parts of the version number (e.g., getMajor(), getMinor(), getPatch()).
• Should provide string representation of the version number via a toString() method.
• Should provide a public method to increment the version number (like what's used in tsc here).