Add new test for extracting symbols

Signed-off-by: Igor Popov <igor.popov89@gmail.com>
Rename variables

Signed-off-by: Igor Popov <igor.popov89@gmail.com>
Extract constant for SYMBOL_WIDTH
Extract method for symbol line
Rename symbolBlock to symbol
Rename test methods
Add test for extracting symbols on other lines
Use scanner directly for extracting lines