exercise 6a
started stats excercise
printf works for single elements of string array
add notes on how to print which parts of the array
counts letters, compares letters to allowed
added notes, commented out code that doesn't work
corrected comment for strlen for fgets
correct character count and output invalid message
consolidated comments
clarified comments; added accurate info on fgets and newline character
remove counter subtraction (fgets newline problem)
check for newline character in sentence, reverse validity check for sentence
comment out print statements for character count
check for full stops and spaces, remove completed TODO comment
remove old, unneeded code
reversed if statement for character count check
check for characters a-z A-Z
remove 'allowed' chars (different check now implemented)
restructured comment
removed count for 'allowed' characters