Multiple change. Added work with item transactions, as well as bug fixes.

The following work has been done:

• Added a wrapper for items in transactions of types in, out, in_cond, out_cond, out_cond_subtype_srv_pay, out_cond_subtype_srv_stake, out_cond_subtype_srv_xchange, out_ext, pkey, receipt, sig, token, token_ext.
• Added function for convert ChainId object to string.
• A wrapper has been added over the dap_sign_t structure; it is taken from the support-4810 branch, as well as read attributes for an object of type Sign, which allow you to get the type of signature, its size and public key.
• Added a function to get a list of items from a transaction.
• Fixed function getting chain net by name.
• Added a function to get a string representation for the dap_chain_addr_t structure wrapper address.
• Fixed function wrapping function getting transaction from ledger.
• The function of creating a hash from the string representation of a given hash has been fixed.
• Added attributes: hash, type, size for the wrapper class of the dap_pkey_t structure. And added a function to get the public key type in string representation using python functions such as print, str.
• For an object of the ChainDatumTx class, the hash and dateCreated attributes have been added, which can be obtained from the object.
• Added a function to return a hash as a string.
• Added a wrapper for dap_chain_tx_in; now you can process the output of information about the inputs of a transaction.
• Added a function to check if the datum contains information about a transaction, and also added a function to get a transaction datum from a datum.
• Added wrapper for atom pointer.