LEN_TRIM: Trimmed length of a character string or of an array (f)

- trimmed_length_of_string = LEN_TRIM(string) ! length of string without counting trailing blanks
examples:
- - CHARACTER str*100/"abc"/
  - trimmed_length_of_str = LEN_TRIM(str) ! 3
- - len_hello = LEN_TRIM("hello ") ! = 5
- trimmed_length_of_array = LEN_TRIM(array) ! length of array without counting trailing zeros
examples:
- - DIMENSION vector(10), matrix(3,4)
  - vector = 0 ! set all elements to 0
  - trimmed_length_of_vector = LEN_TRIM(vector) ! 0
- - vector = (101,102,103) ! assignment to the first 3 elements
  - trimmed_length_of_vector = LEN_TRIM(vector) ! 3
- - matrix = $ ! assign 1, 2, .. 12 to matrix
  - trimmed_length_of_matrix = LEN_TRIM(matrix) ! 12
- - len_hello = LEN_TRIM("hello ") ! = 5
⇒ Length of a character string or of an array