Feature request: provide API to add blank lines

This is a simple feature request with no real business value but makes it a lot more easier to read through the source code.

# Usage

block.addStatement(getFactory().createCodeSnippetStatement("int i = 1"));
block.addStatement(getFactory().createBlankLine());
// or block.addBlankLine()
block.addStatement(getFactory().createCodeSnippetStatement("for (; i < 0; i++) {}));

# Current result

int i = 1;
for (; i < 0; i++) {}

# Expected result

int i = 1;

for (; i < 0; i++) {}