Trac #15550 implement the Kirchhoff-Symanzik polynomial

Also implements cycle_basis for graphs with multiple edges
And xadd an 'output' keyword to cycle_basis, is_tree and is_forest
Allowing to obtain cycles as list of edges
Trac #15550: Review, small changes to the doc
small fix in API.pxi
Starting work on pow_computer_flint
updated FLINT/ paths
rebase fixup
working on flint powcomputers
more progress on pow computer flint
added missing interrupts
pow computer flints needs c
added functions for fmpz
fmpz_poly_struct
Added-more-flint-functions
Working-on-pow_computer_flint
Fix-redeclaration-of-deg
added-flint-functions
fixed-a-missing-self
Added-qadic_flint_CR
creating parents
working on creating parents