Many corrections in preprocessing of strings

Better signatures and string detection

Better detection of string-like types and handling of char arrays

Changing the way we deal with string initialisation from array
Factorized part of type recognition and added StringBuilder and
CharSequence to the list of java classes that should be
considered as string.

Changed the way we deal with StringBuilders: instead of having a map
we add an assignment to the instructions.

We also detect char arrays and handle them better.
We now use substring and copy functions for initialisation from char
array since the argument are always
transformed into refined strings.

For each string returned by a string function we also add into the
java_string_to_cprover_string map a string_exprt.

Corrected detection of typecast in make_cprover_string_assign

Ensuring refined_string arguments of function applications are string_exprt

Correct string_refine_preprocesst constructor.
Order of initialisation is now the same as the order of
declaration.
This was picked up by g++ and clang.

Added signatures for some StringBuilder functions.

Removed map java_to_cprover_string and adapt signature for
side effects.
The usage of a map is not correct since strings can be modified by
side effects. Signature is necessary for StringBuilders to be assigned
in the right way with methods with side effects.

Assign all string_exprt to refined string symbols in preprocessing.
This makes it then easier to debug and to find
witnesses for counter examples in the solver.

Make signatures take priority over actual type and add signature
for intern.

Linting corrections

Adding malloc for char arrays for String.toCharArray

Fixing preprocessing of string function with side effect

This fixes problems we were getting with some StringBuilder functions.
The return value should contain a pointer to the original
StringBuilder and the fields of the StringBuilder should be filled
with the result of the function call.

Corrected mistake in preprocessing of string functions with side effects

char array assignements returns a string_exprt

This is to be uniform with other preprocessing functions also
returning string_exprt

Preprocessing for StringBuilder.append on char array

Corrected update of signature and commented out some unused code

Corrected the initialization from char array

We cannot use the substring function because the meaning of the third
argument is different between `String.<init>([CII)` and
`String.substring(SII)`

Using new id for conversion between char pointer and array

Cleaning of preprocessing for strings

Removed useless functions and merged some maps

Make a copy of the function call to be modified

Removed redeclaration of location

Author: romainbrenguier