... and use sstreams instead of sprintf

This commit fixes the formatting warning in the Mutation classes.

- For mut_type() and sense() calls, we changed the PRId8 format specification
  to PRId32
- For the -1 constants, we explicitly cast them to the right size
  (int8_t or int16_t) to reflect the format specification

This commit gets rid of the -Wdefaulted-function-deleted warning
that popped up in Mutation-derived classes.

It came from the fact that Mutation.h had these definitions:

               |     copy      |      move
----------------------------------------------------
constructor    |   default     |    default
----------------------------------------------------
operator       |   delete      |    delete

whereas the derived classes had the following:

               |     copy      |      move
----------------------------------------------------
constructor    |   default     |    delete
----------------------------------------------------
operator       |   default     |    delete

This meant that the move operator was defaulted in the base class
but deleted in the derived classes, producing the warning (the
discrepancy was introduced in 6615dbb4).

This commit deletes all copy operators, leaving only copy constructors,
which are used in the Clone() method shared by Mutation classes.

Note that in *HT classes, the copy constructor is defaulted but
the classes contain pointers, so there might be a memory issue when
calling the constructor.

Magic command for reference:
find ! -path '*test*' ! -path './libaevol/SFMT-src-1.4/*' \( -name '*.cpp' -o -name '*.h' \) -print0 | xargs -0 sed -i -r 's/\bget_(\w+)\b/\1/g'

Looking forward to honour Google Style guide, the purpose is to rename getters
from get_var() to var(). Many of such renames cause conflicts, though. In this
commit, only the safe names were changed.

grep -rEo '\bget_\w+\(' --include '*.h' --no-filename --exclude-dir tests \
 | sed -e 's/get_//' -e 's/($//' \
 | sort -u \
 | xargs -n 1 -I% sh -c "grep -roq '\b%\b' --include '*.cpp' --include '*.h' --exclude-dir tests || echo %" \
 | xargs -n1 -I% sh -c "find ! -path '*test*' ! -path './libaevol/SFMT-src-1.4/*' \( -name '*.cpp' -o -name '*.h' \) -print0 \
 | xargs -0 sed -i -r 's/\bget_%\(/%\(/g'"

Yes. I know...

http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Function_Names

Took aevol_run.cpp's header as reference header and set it for all Aevol source files.

Instead of a single class with switches everywhere, mutations are now
handled through a proper polymorphism.

Here is the class hierarchy:
Mutation
  <-- LocalMutation
        <-- PointMutation
        <-- SmallInsertion
        <-- SmallDeletion
  <-- Rearrangement
        <-- Duplication
        <-- Deletion
        <-- Translocation
        <-- Inversion
  <-- HT
        <-- InsertionHT
        <-- ReplacementHT