Adding basic tests for OP_CSV inside of script_tests.json

Changing NOP3 op name to OP_CHECKSEQUENCEVERIFY, renaming instances of OP_NOP3 in script_tests.json to CHECKSEQUENCEVERIFY

Cleaning up NOP3 comment

Re-adding test cases that were accidentally deleted, removing dupicated test case, fixing formatting

Removing re-labeling of OP_NOP3 to OP_CSV

Fixing whitespace issues

src/test/data/script_tests.json

@@ -701,6 +701,8 @@
 ["0x17 0x3014021077777777777777777777777777777777020001", "0 CHECKSIG NOT", "", "OK", "Zero-length S is correctly encoded for DERSIG"],
 ["0x27 0x302402107777777777777777777777777777777702108777777777777777777777777777777701", "0 CHECKSIG NOT", "", "OK", "Negative S is correctly encoded"],
  
+["2147483648", "NOP3", "CHECKSEQUENCEVERIFY", "OK", "CSV passes if stack top bit 1 << 31 is set"],
+
 ["", "DEPTH", "P2SH,STRICTENC",   "EVAL_FALSE", "Test the test: we should have an empty stack after scriptSig evaluation"],
 ["  ", "DEPTH", "P2SH,STRICTENC", "EVAL_FALSE", "and multiple spaces should not change that."],
 ["   ", "DEPTH", "P2SH,STRICTENC", "EVAL_FALSE"],
@@ -1820,5 +1822,12 @@
     "P2SH with CLEANSTACK"
 ],
 
+["CHECKSEQUENCEVERIFY tests"], 
+["", "NOP3", "CHECKSEQUENCEVERIFY", "INVALID_STACK_OPERATION", "CSV automatically fails on a empty stack"],
+["-1", "NOP3", "CHECKSEQUENCEVERIFY", "NEGATIVE_LOCKTIME", "CSV automatically fails if stack top is negative"],
+["0x0100", "NOP3", "CHECKSEQUENCEVERIFY,MINIMALDATA", "UNKNOWN_ERROR", "CSV fails if stack top is not minimally encoded"],
+["0", "NOP3", "CHECKSEQUENCEVERIFY", "UNSATISFIED_LOCKTIME", "CSV fails if stack top bit 1 << 31 is set and the tx version < 2"],
+["4294967296", "NOP3", "CHECKSEQUENCEVERIFY", "UNSATISFIED_LOCKTIME",
+  "CSV fails if stack top bit 1 << 31 is not set, and tx version < 2"],
 ["The End"]
 ]