Add support for BOL and EOL terms in the Regex to CVC4 compiler

Relates to #99
Add test for character classes
Add support for .* in the Regex to CVC4 compiler

Relates to #99
Add support for string.prototype.search (positive case)

Relates to #99
Add regex support for string.prototype.replace

Related to #99
Fix bug in constraint log output during errors and improve output.
Fix the depth-limit.html test case not to depend on the solver version.
Merge branch 'master' of github.com:cs-au-dk/Artemis
Update .gitignore to exclude unit test build files.
Remove left-over lines from boolean-simple to match boolean-simple-negation.
Concolic test case for issue #107.
Added newlines
Merge branch 'master' of github.com:cs-au-dk/Artemis
Fix EP visualization script and improve concolic test suite output.
Merge branch 'master' of github.com:cs-au-dk/Artemis
Add PC-level support for null/undefined constraints and string.prototype.match

All current solver backends default to error if they encounter these new expressions.

Related to #99
Merge constraint logs into cvc4solver.cpp

Notice that only the CVC4 solver will write to the contraint log. Legacy solvers are not supported.

All sat/unknown/unsat constraint files are now moved into /tmp/constraints and an index of the files is emitted to /tmp/constraintindex - this is useful for our upstream SMT friends.

Fixes #100
Update CVC4 to the newest release
Support symbolic null and partial support for string.prototype.match

string.prototype.match is now implemented (positive/negative case) with the following limitations:
 - Group 0 (array access on index 0) is symbolically represented by the entire source string, and not the matched substring
 - Group 1...n (array accesses above index 0) is not supported

Relates to #99
Delete references to unused constraint log