完善测试文件生成脚本, 当文件开始是用户的注释时, 保留用户注释
Merge https://github.com/golang-zh/gccgo
完善测试脚本

1. 完善测试脚本的文档
2. 增加文件名冲突的检测
3. 跳过已经生成过的测试文件
简化测试文件脚本生成的头部注释格式
重新生成测试文件, 简化头部注释
Merge pull request #4 from chai2010/master

完善生成脚本, 避免用户注释被覆盖
tests/expected_integer_or_boolean_type.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/expected_pointer.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/invalid_comparison_of_nil_with_nil.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/incompatible_types_in_binary_expression.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/integer_division_by_zero.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/shift_of_non_integer_operand.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/shift_count_not_unsigned_integer.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/negative_shift_count.go: add.

Signed-off-by: minux <minux.ma@gmail.com>
tests/len_larger_than_cap.go: add.

Signed-off-by: minux <minux.ma@gmail.com>