Looks up the given filename from the internal file buffer table, and returns the lines within the file. If the file does not already exist within the table, it will be read from the filesystem. If it has been read before,
the loaded source file if it was found in memory, otherwise null
See Implementation
Looks up the given filename from the internal file buffer table, and returns the lines within the file. If the file does not already exist within the table, it will be read from the filesystem. If it has been read before,