sweep browser TTL display issues and DA/AD epoch potential weirdness

[t-b]

FTP: issue-2125

[t-b]

Enable AD/DA/TTL and enable Visualize epochs for sweep 30:

  Message: "Unexpected number of matches"
  Please provide the following information if you contact the MIES developers:
  ################################
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Stacktrace:
  BSP_CheckProc_ChangedSetting(...)#L1293 [MIES_BrowserSettingsPanel.ipf]
UpdateSweepPlot(...)#L6405 [MIES_MiesUtilities.ipf]
DB_UpdateSweepPlot(...)#L473 [MIES_DataBrowser.ipf]
PostPlotTransformations(...)#L3975 [MIES_MiesUtilities.ipf]
LayoutGraph(...)#L2689 [MIES_MiesUtilities.ipf]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Time: 2024-05-24T22:19:29+02:00
  Locked device: [ITC18USB_Dev_0]
  Current sweep: [30]
  DAQ: [DAQ_NOT_RUNNING]
  Testpulse: [TEST_PULSE_BG_MULTI_DEVICE]
  Experiment: C57BL6J-684963.02.04.01_pislocin_puff_2023_07_19_141829 (Packed)
  Igor Pro version: 9.0.6.1 (56657)
  MIES version:
  Release_2.7_20230809-750-g85030efee
Date and time of last commit: 2024-05-24T13:13:00+02:00
Submodule status: 
-bcbf5729ee85da80ea0f14dd5a42b55ed8fda47e Packages/IPNWB
-d229d451f35e88b8c38edb8c26533acfbc3fd10f Packages/doc/doxygen-filter-ipf
-d557db885f2077bb1998cf9ef938477881c44775 Packages/igortest
  ################################

The assertion is thrown because the code assumes that we have TTL epoch info, but we don't for old data.