Increase version number to 1.7

* Update README.txt so that Python 3.7 is required

README.txt

@@ -1,6 +1,6 @@
 
-              SLiVER 1.6
-              February 2021
+              SLiVER 1.7
+              July 2021
 
 Symbolic LAbS VERifier
 
@@ -26,7 +26,7 @@ cbmc-simulator    A build of CBMC 5.4
 
 To install SLiVER, please follow the steps below:
 
-    1. install Python 3.5 or higher
+    1. install Python 3.7 or higher
 
     2. create a directory, suppose this is called /workspace
 
@@ -46,12 +46,14 @@ The following command should instead report that a property is violated:
 
     ./sliver.py --steps 18 --fair examples/boids-aw.labs birds=4 delta=13 grid=10
 
-Use the --backend=<cbmc|cseq|esbmc> option to select a different
+Use the --backend=<cbmc|cseq|esbmc|cadp> option to select a different
 verification backend. 
-Please keep in mind that ESBMC support is still experimental, therefore:
+Please keep in mind that:
+
+  1. We only bundled the CBMC executable as part of this package. Therefore,
+     cadp, cseq, or esbmc must be obtained separately.
+  2. Our counterexample translation does not support esbmc yet.
 
-  1. The esbmc executable is not provided as part of this package
-  2. Our counterexample translation only supports CBMC and CSeq.
 
 Invoking the tool without options:
 

__about__.py

@@ -6,5 +6,5 @@
 __summary__ = "The SLiVER LAbS VERification tool"
 __uri__ = "https://github.com/labs-lang/sliver"
 
-__version__ = "1.6"
-__date__ = "February 2021"
+__version__ = "1.7"
+__date__ = "July 2021"

sliver.py

@@ -78,7 +78,7 @@ def make_filename(file, values, bound, fair, sync, language):
 @click.option('--verbose', **DEFAULTS("verbose", default=False, is_flag=True))
 def main(file, backend_arg, fair, simulate, show, values, **kwargs):
     """
-* * *  SLiVER - Symbolic LAbS VERification. v1.6 (February 2021) * * *
+* * *  SLiVER - Symbolic LAbS VERification. v1.7 (July 2021) * * *
 
 FILE -- path of LABS file to analyze