added limit of parallel open files
added comment to methods, removed one folder
added sync.WaitGroup, removed 2 not needed for loops
fixed deadlock, faster checksum calculation, added total remove size
only limited amount of goroutines are created now
added new calculateChecksum function with fixed buffer size
buffer size is now constant
remove not needed prints
reduced number of open files, reduced buffer size to 30MB, add triggering garbage collector
formatted with go fmt