Release Note: Improved CompileCommand Flag

The CompileCommand flag has an option type that has been used for a collection of sub commands. These commands weren't verified for validity so spelling mistakes lead to the command being ignored. They had the form:
```
-XX:CompileCommand=option,<method pattern>,<option name>,<value type>,<value>
```

All option commands now exist as ordinary commands with this form:
```
-XX:CompileCommand=<option name>,<method pattern>,<value>
```

The option name is verified and the type is inferred. Helpful error messages are given if the command name doesn't exist, or if the value doesn't match the type of the command. All command names are case insensitive.

The old syntax for option commands can still be used. Verification that the option name, value type, and value is consistent has been added.

All available options can be listed with:

```
-XX:CompileCommand=help
```