Updating bigint for portability, uses builtin uintmax_t
Checked bigint compatibility. Added comments to hashlife.c
Did what I claimed having done in the previous commit

- The struct BigInt is now opaque. Changes to conversion.[ch] are necessary as it relies on a particular implementation of it, which is obselete now.

- A wide int type is used
Minor comment
Minor corrections
Minor corrections (2)
Parser of plain text format

- Any number of optional lines starting with '!', mostly ignored (1)

- followed by any number of lines with the same number of columns, containing either '.' or 'o' (15th letter)

- and an empty line

1. Some optional lines can be of the form

        !s2345/b123456

    denoting some rule. Only the last one is recorded.
New code style:

- if ( blablabla ) // Note the spaces separating the condition from the brackets
Opacified dynamic array implementation
Decoupling map representations
Runlength encoded format
Input-output rewritten