use syntax from ACSL reference manual for annotations
add some unuseful files (for ACSL dev) in gitignore
simplify disjoint/complete clauses for po_hi_types
add PROVER_OPTIONS variable (default to "") to add options for
prover (cpu time limit etc.)
add proof-wp-report goal and WP_FILTER option
change specification of po_hi_types.h using .. ACSL operator (no need
for behaviors now)
simple C test file for __po_hi_copy_array specification