* Adds get_sysvar_with_account_check2 for ABIv2.
* Replaces get_signers() and get_sysvar_with_account_check() in system_instruction_processor.
* Replaces KeyedAccount by BorrowedAccount in nonce_keyed_account.
* Moves TransactionContext::get_program_key() to InstructionContext::get_program_key().
* Removes TransactionContext::get_loader_key().
* Test full program and loader executable account chain in BPF loader.
* Moves stack_height of the instruction_trace into InstructionContext.
* Uses nesting_level instead of stack_height internally in transaction_context.rs
* Uses the instruction_trace instead of the instruction_context_stack internally.
* Adds feature gate: record_instruction_in_transaction_context_push.
* Adds BorrowedAccount::check_sysvar().
* Adds BorrowedAccount::get_data_mut().
* Implements account resizing in BorrowedAccount.
* Exposes is_signer() and is_writable() in InstructionContext.
* Removes AccountMeta and get_instruction_accounts_metas().
* Makes throwing errors in BorrowedAccount optional.
* Removes result return values from BorrowedAccount.
* Replaces from_keyed_account() by SysvarCache in stake instruction.
* Replaces from_keyed_account() by SysvarCache in system instruction processor.
* Removes from_keyed_account().
Moves check_sysvar_keyed_account() into sysvar_cache.rs
* Removes tests which test for incorrectly serialized sysvars.
* Unifies SysvarCache filling in the runtime and tests.
Removes new_mock_with_sysvars_and_features()
Removes mock_process_instruction_with_sysvars().
Replaces from_keyed_account() by SysvarCache in vote processor.
* Replaces from_keyed_account() by SysvarCache in BPF loader.
* Adds TEST_DUPLICATE_PRIVILEGE_ESCALATION_SIGNER and TEST_DUPLICATE_PRIVILEGE_ESCALATION_WRITABLE.
* Moves CPI privilege verification out of deduplication loop.
* Makes error handling in BorrowedAccount optional.
Adds BorrowedAccount ::get_rent_epoch().
Exposes InstructionContext::get_index_in_transaction().
Turns accounts and account_keys into pinned boxed slices.
* Introduces "unsafe" to InvokeContext::push().
* Turns &TransactionContext into &mut TransactionContext in InvokeContext.
* Push and pop InstructionContext in InvokeContext.
Makes test_process_cross_program and test_native_invoke symmetric.
Removes the borrow check from test_invoke_context_verify.
* Removes keyed_accounts from prepare_instruction()
* Removes usage of invoke_stack.
* Removes keyed_accounts from program-test.
* Removes caller_write_privileges.
* Removes keyed_accounts from BPF parameter (de-)serialization.
* Turns compute_units_consumed of ProcessInstructionResult into a &mut parameter.
* Removes second nesting level from test_process_instruction_compute_budget().
* Makes test_process_cross_program and test_native_invoke symmetric.
* Unifies test_process_cross_program(), test_native_invoke() and test_process_instruction_compute_budget() into test_process_instruction().
* Adds TransactionContext, InstructionContext and BorrowedAccount.
* Redirects the usage of accounts in InvokeContext through TransactionContext.
Also use the types declared in transaction_context.rs everywhere.
* Adjusts all affected tests.
* Unifies all InstructionRecorders of a transaction into one.
* Stops explicitly compiling CPI instructions for recording,
uses the indices gathered from instruction_accounts instead.
* Removes message::Message from invoke_context.rs completely.
* Simplifies sol_invoke_signed() of program-test
* Start search for non program accounts at front (instead of the back).
Program and programdata accounts use rposition(), everything else uses position().
* Introduces InstructionAccount which is like AccountMeta but uses an index instead of a Pubkey
* Renames InvokeContext::create_message() to InvokeContext::prepare_instruction()
* Removes Message and CompiledInstruction from InvokeContext interfaces.
* Resolves TODOs of sol_invoke_signed() in program-test.
* Moves CompiledInstruction::visit_each_account() into invoke_context.rs