some additions to core and test for them

tests/core_bitops.expected

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+2
+7
+5
+-1
+8
+8
+4
+-4
+6
+4
+3
+7
+8
+4
+4
+1
+3
+1
+16838

tests/core_bitops.sl

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+import ../stdlib/stdlib.sl
+import ../stdlib/io.sl
+
+word main
+    6 3 band puti cr
+    6 3 bor puti cr
+    6 3 bxor puti cr
+    0 bnot puti cr
+    1 3 shl puti cr
+    1 3 sal puti cr
+    8 1 shr puti cr
+    8 neg 1 sar puti cr
+    5 inc puti cr
+    5 dec puti cr
+    3 7 min puti cr
+    3 7 max puti cr
+    1 3 rol puti cr
+    8 1 ror puti cr
+    5 1 4 clamp puti cr
+    0 1 4 clamp puti cr
+    3 1 4 clamp puti cr
+    time 0 > puti cr
+    1 mem swap !
+    rand puti cr
+    0
+end

tests/core_bitops.test

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+python main.py tests/core_bitops.sl -o ./build/core_bitops > /dev/null && ./build/core_bitops