doc: doc: improve documentation of objects (2)

  [`getStartPoint()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a1bddb8af8c3f64067bf8767c5a435117),

  [`getEndPoint()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a1ae55b27c872c7adfa6fd890f2f83195))

- Global time when the track had its first and last appearance (

  [`getGlobalStartTime`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a913166027c8a2dec9ffba22361b289f1),

  [`getGlobalEndTime`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a01377a4a6f447bc85b92e306da5989c3))

  [`getGlobalStartTime()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a913166027c8a2dec9ffba22361b289f1),

  [`getGlobalEndTime()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a01377a4a6f447bc85b92e306da5989c3))

- Initial and final kinetic and total energy (

  [`getKineticEnergyInitial()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a9998511439c665d777d65779f9f9dcdf),

  [`getTotalEnergyInitial()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCTrack.html#a25c481bd56d0c2ab8ba15c4292c8ecc7),

For more details refer to the [code reference](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCParticle.html).

## SensorCharge

This is a meta class for a set of charges within a sensor. SThe properties of this object are inherited by

[DepositedCharge](#depositedcharge) and [PropagatedCharge](#propagatedcharge) objects.

Main parameters:

- The position of the set of charges in the sensor in local and global coordinates (

  [`getLocalPosition()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1MCParticle.html#a3ab0b177b8b64535057d98bd3238cae3),

  [`getGlobalPosition()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#adcf461c7b657982725c8abad6ff74ac4))

- The associated time of the set of charges in local and global coordinates (

  [`getLocalTime()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#a365ea8e1f752290ffba385a5fdd0d52d),

  [`getGlobalTime()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#ad42d8e19a3e01bf9204d002ec9370018))

- The sign of the charge carries (

  [`getSign()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#a70e90b3397690567c5e5e98b441108d6))

  and the amount of charges in the set (

  [`getCharge()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#adab95a4c287dc8b3ae106e07a22214f6))

- The carrier type to check if the charge carriers are electrons or holes (

  [`getType()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html#a903e762bc987c43fe1e8128f400e4ea3))

For more details refer to the [code reference](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1SensorCharge.html).

## DepositedCharge

The set of charge carriers deposited by an ionizing particle crossing the active material of the sensor. The object stores

addition, the time (in *ns* as the internal framework unit) of the deposition after the start of the event and the type of

carrier (electron or hole) is stored.

Main parameters:

- Everything from [SensorCharge](#sensorcharge)

- The [MCParticle](#mcparticle) that created the deposited charge (

  [`getMCParticle()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1DepositedCharge.html#a371c2f081846e00b6ea5aaaba049dbb7))

For more details refer to the [code reference](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1DepositedCharge.html).

## PropagatedCharge

another process. Timing information giving the total time to arrive at the final location, from the start of the event, can

also be stored.

The state of the charge carrier at the end of the propagation can be retrieved via the `getState()` method. The following

values are available:

Main parameters:

- Everything from [SensorCharge](#sensorcharge)

- The associated [DepositedCharge](#depositedcharge) object (

  [`getDepositedCharge()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1PropagatedCharge.html#a2faa699e53a1809e645d0556ce924345))

- The associated induced pulses, if any (

  [`getPulses()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1PropagatedCharge.html#a6dfb809cfda7bab0893292c4861e85d3))

- The carrier state of the charge carriers described below (

  [`getState()`](https://allpix-squared.docs.cern.ch/reference/classallpix_1_1PropagatedCharge.html#ac14ea433405562d18a6113948707552f))

The following values for the carrier state are possible:

- `CarrierState::UNKNOWN`:

  The final state of the charge carrier is unknown, for example because it might not have been provided by the used