This still needs some further supporting pieces, but the plan is for this to
eventually supersede Node::constant_fold().

We moved from building the latest version of AFL from source, to using the afl++
package in Ubuntu Focal. However, this package lately does not seem to work.
Specifically it is unable to find libgmp when used as a compiler in combination
with CMake. Reverting to the old AFL setup appears to fix this.

This reverts 49444277.

Fix Request For Sponsorship url in release checklist

These no longer work as support for older XCode has been dropped. There is no
point trying to work around this when Homebrew users are likely on the latest
XCode.

Github: related to #203 "murphi2c produces broken print code"

Github: closes #203 "murphi2c produces broken print code"

This is a breaking behaviour, but it will make resolving #203 simpler.

Github: related to #203 "murphi2c produces broken print code"

Not yet used, but we will need these in order to emit bounds in a couple of
places.

Github: related to #203 "murphi2c produces broken print code"

When emitting a print statement for a Murphi put statement of a string, the
string was incorrectly escaped. The value in a Put node in this case is already
naturally escaped, so needed no further escaping.

This seems to have been broken more or less forever, but apparently C compiler's
accepted this as a non-prototyped function. This was exposed as an error by a
recent transition to Apple clang version 12.0.0 which defaults to C99, requiring
stricter rules around pre-prototyping functions. We should probably set a C
standard explicitly during compilation in testing.

To avoid a dependency on Ninja, as it is not installed by default in Travis and
installing it takes valuable time.

Github: closes #202 "remove section ordering restriction"

This opens the way to things like a constant or range limit that uses a
previously defined function. Though this is not yet supported.

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

Note that this has the following user-visible effects:
  * White space in C code produced by murphi2c has changed slightly; and
  * XML produced by murphi2xml no longer nests declarations, functions and rules
    under their own sections under <model>, but instead just directly under
    <model>.

Github: related to #202 "remove section ordering restriction"

The XML output is now also considered legal when declarations, functions and
rules appear directly as children of the 'model' element. That is, we no longer
require them to be nested under 'decls', 'functions', 'rules', respectively

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

After some upcoming changes to relax section ordering restrictions, this kind of
node reordering will have some undesirable side effects. In order to pre-empt
this, we take advantage of the fact that fields are only being reordered to get
more optimal offsets. Since the offset of state variables is stored within them
and not calculated dynamically, we can simply update their (explicit) offsets,
and leave their ordering as-is, neatly side stepping this upcoming issue.

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

Github: related to #202 "remove section ordering restriction"

While this is currently rejected, we may consider this legal in future.

Github: related to #202 "remove section ordering restriction"

The idea is to move to a less error prone visitor pattern. By requiring
visitation dispatch to be implemented on classes, we ensure a new AST node
cannot be introduced without handling its visitation support.

This is already available in tempfile.