Scripts for performance analysis

There are now two scripts that analyse the runtime and memory consumption
of different AST construction algorithms and print this data.

Runtime analysis:
    python -m analysis.runtime <n_from> <n_to> <n_step> <m>

    n_from, n_to, n_step - Determine the lengths of strings in auto-generated
                           string collections during analysis. These generated
                           collections are "worst-case" ones.
    m - Number of strings in each collections (100 by default).

    The script will compare the performances of all the 3 basic algorithms
    ("easa", "ast_linear", "ast_naive")

Memory analysis:
    python -m analysis.memory <algorithm> <n_from> <n_to> <n_step> <m>

    algorithm - "easa"/"ast_linear"/"ast_naive". Note that this script can
                analyse only one algorithm at a time.
    n_from, n_to, n_step, m - Auto-generated string collections paratemers,
                              as in runtime analysis.
Docs formatting

Added bulleted list for CLI options