trac #16248: Some trivial Orthogonal Arrays
trac #16277; Merged with #16269
trac #16277: Merge with #16248
trac #16277: Merged with #16058
rewrote two if statements to make the code more readable
minor changes in some docstrings
"== None" to "is None" in docstrings (finial_word_out)
"== None" to "is None" in code (in composition)
trac #16277: MOLS constructions rom the Handbook of Combinatorial Designs
trac #16235: A pair of orthogonal latin squares of order 10
trac #16277: Reviewer's remarks
trac #16277: Yet another construction
trac #16277: Merged with updated #16272

Conflicts:
	src/sage/combinat/designs/orthogonal_arrays.py
trac #16277: From availability to existence and broken doctests
trac #16286: Allow k=None in MOLS/TD/OA
trac #16277: removes a doctests that appears several times already
trac #16277: Merged with updated #16231

Conflicts:
	src/sage/combinat/designs/bibd.py
	src/sage/combinat/designs/latin_squares.py
trac #16286: Merged with updated #16272
trac #16235: Merged with updated #16286
trac #16286: more doc, more tests