Fix the bug of spliting strings of configuration values.

Some configuration parameters accept the space or comma separated values. For example, the `defaultIncludes`, `defaultExcludes`, `optionSet`, `defineSet`,  `undefineSet`, and the `compileOrder`. 

The `Compiler.getCompiler()` function will split those values and add them to the list of compiler arguments.

But the implementation of `Compiler.getCompiler()` failed to filter the empty sub-strings, and failed to trim the sub-strings, produced by the spliting.

This patch simply use a regular expression as the separators to filter the empty sub-strings and trim the resulting sub-strings.