remove another custom linux shim in favour of compat/ directory

enable -Wstrict-prototype and -Wunused-variable in Linux build

add a -C option which sets the amount of context lines in unified diffs

add support for ignoring whitespace (-w option) Tests grow the ability to call diff with options. Options to use are encoded in the test file name as a single dash followed by a string of option letters. E.g. -wp for 'ignore whitespace' and 'do patience'

avoid include statements in header files; make each .c pull in what's needed

replace enum diff_rc errors with plain errno values

fall back on file i/o in case an input file cannot be memory-mapped

KNF: use max 80 columns

diff cmdline tool: allow using Patience by -p arg

remove code dup of diff_main() invocation for plain vs unidiff

diff.c: move two #include to the top

myers: permit ~4Mb of state

switch default to unidiff

initial commit