Feat add ttree merger (#12)

* beginning tree merger

* progress

* progress on merging

* Very messy right now, but figured out the dtype issues that were preventing writing var * float...

* Separated hadd and merge/add, merges better now but issue with uproot Model_TAxis_v9 writing back

* save progress

* Can merge certain files, but has the copy issue to be resolved

* Simplified merge, need to work on grouping

* saving progress: fixed duplicating counters, now working on extend issue with zipped data

* Able to be built, tests pass

* formatting

* formatting

* formatting

* formatting

* formatting

* formatting, pylint having issues with similar code

* formatting, pylint having issues with similar code

* removed main hadd function

* more formatting

* import error fix

* import error fix

* import error fix

* docs

* docs

Author: zbilodea

src/odapt/__init__.py

@@ -6,6 +6,9 @@
 from __future__ import annotations
 
 from odapt._version import __version__
-from odapt.operations import hadd  # noqa: F401
+from odapt.operations import (
+    hadd,  # noqa: F401
+    merge,  # noqa: F401
+)
 
 __all__ = ["__version__"]

src/odapt/operations/__init__.py

@@ -1,3 +1,4 @@
 from __future__ import annotations
 
-from odapt.operations.hadd import hadd, main  # noqa: F401
+from odapt.operations.hadd import hadd_1d, hadd_2d, hadd_3d  # noqa: F401
+from odapt.operations.merge import hadd_and_merge  # noqa: F401