RNG-seeding bug fix and readability improvements

[andrsmit]

There were two commits added here:

1. c323985
   • The inconsistent usage of tabs/spaces for indentation was standardized. Each layer of indentation is now created with 2 space characters (no tabs).
   • I removed indentations from empty lines.
   • A typo in a printout statement was corrected ("Swicth" -> "Switch")
   • Some extra spaces/tabs tacked on to the end of lines were removed.
2. c0a5bf5
   • Originally this event generator initialized the seed for ROOT's global "gRandom" pointer by doing "gRandom->SetSeed(seed);" at the beginning of the code. That was removed at some point during the recent upgrades made last year, and was replaced with a locally-defined pointer to a TRandom3 (called "fRandom"). However, the "gRandom" pointer is still being used later on in the code to generate (pseudo) random values for the photon beam energy for each event. Without explicitly setting the seed for "gRandom" as well, this led to the same repeated sequence of beam energies on each execution of this code. To correct this, I added a line "gRandom = fRandom;" after the "fRandom" get's initialized.
   • There was previously an option for users to pass in a custom, fixed seed for the RNG using the "-s" flag during run time. This feature also disappeared with the updates that were made last year. The integer "seed" was still being defined and set, but was unused - leading to compiler warning messages. I added this feature back in by defining a new integer, "customSeed", which is 0 by default, but get's set to 1 whenever the user provides the "-s" flag. Otherwise, the same algorithm for determining the seed based on the timestamp is used.

[gluex]

Test status for this pull request: SUCCESS

Summary: /work/halld/pull_request_test/halld_sim^gen_primex_eta_he4_rng_fix/tests/summary.txt
Logs: /work/halld/pull_request_test/halld_sim^gen_primex_eta_he4_rng_fix/tests/log

Build log: /work/halld/pull_request_test/halld_sim^gen_primex_eta_he4_rng_fix/make_gen_primex_eta_he4_rng_fix.log
Build report: /work/halld/pull_request_test/halld_sim^gen_primex_eta_he4_rng_fix/report_gen_primex_eta_he4_rng_fix.txt
Location of build: /work/halld/pull_request_test/halld_sim^gen_primex_eta_he4_rng_fix