LICENSE and link to travis fixes

new release 0.5.4

fixed color output

release 0.4.16

- Renamed 'stack' operations (more verbose names).
- Using queue to encode XORs to avoid quadratic worst-case.
- Reusing the trail during restarts using 'matching trail level' (MTL).

release 0.4.7

- Almost complete colored solver messages (in 'report' etc.).
- Support for reading and encoding XNF (CNF with OR and XOR clauses).
- New makefile goals: test-two-ways, test-all-pairs, test-all-triples.
- Binary search in two-way combinatorial tester 'gencombi'.
- Code clean-up: sorted statistics fields, moved some internal code up.
- Using stable radix sort in 'reduce' allowed to remove clause ids.
- Radix sorting (to speed-up sorting of 'analyzed' stack).

release 0.4.2 - see NEWS.md

saving phases fixed (pointer increase by two - thanks to Mathias Fleury)
using assigned variables instead of trail height for target/best phases
scripts have now colors (thanks to Daniel Le Berre)

improved markdown in READMEs

VSIDS

drat-trim search and testing in tatch.sh fixed

binary proofs + testing of proofs