Here are the classes, structs, unions and interfaces with brief descriptions:

[detail level 12]

CButtonReader	Read button state from a voltage ladder-style keypad
CCascadeHumidistat	Control humidity using cascade PID: outer PID loop sets setpoints of two inner flow controllers, which drive a solenoid valve each. Adjust the public setpoint variable and call update()
CCharDisplayUI	TUI for 16x2 character LCD. Holds a reference to a LiquidCrystal instance for writing to display. Displays current mode, PV, SP, and CV the first line of the display, and temperatures on the second line. Use keypad to adjust setpoint (UP/DOWN for fine, LEFT/RIGHT for coarse)
▼CConfigPar	A class for storing references to variables of various types (uint8_t, uint16_t, or double)
CVar
CConfigStore	Config store containing variables, which can be stored in EEPROM
CController	Base class for a controller. Owns a PID instance, and holds a reference to a ConfigStore instance
CControllerUI	User interface (display and input) for humidistat. Hold references to ButtonReader for keypad input, and Humidistat for updating the humidity setpoint
CDHTHumiditySensor	Implementation of the HumiditySensor interface for the DHT22/AM2302 sensor
CEEPROMConfig	Load/save an (internal) ConfigStore in EEPROM
CFlowController	Controls flow. Holds a reference to a FlowSensor instance
CFlowSensor	Read flow rate using a Omron D6F-P0010 MEMS flow sensor
CGraphicalDisplayUI	TUI for 128*64 px graphical display using U8g2. Holds references to a U8g2lib instance for writing to display, an EEPROMConfig instance to edit the config, and to a Humidistat instance to show/edit its state
CHumidistat	Base class for a humidistat. Holds a reference to a HumiditySensor instance
CKs0256VoltLadder	Implementation of the VoltLadder interface for the Keyestudio Ks0256 keypad
CKs0466VoltLadder	Implementation of the VoltLadder interface for the Keyestudio Ks0466 keypad
CPID	PID controller in parallel form implemented in floating-point arithmetic. Features Derivative-on-Measurement, anti-windup through conditional integration, bumpless transfer, and feed-forward
CPoint	Point: a vector of a time and setpoint value
CSerialLogger	Logs humidistat data over serial
CSetpointProfileRunner	'Runs' a setpoint profile
CSHTHumiditySensor	Implementation of the HumiditySensor interface for the Sensirion SHT85 sensor
CSingleHumidistat	Control humidity using PID by driving two solenoid valves. Adjust the public setpoint variable and call update()
CSPProfile	Setpoint profile: a label and a span over Points
CThermistorReader	Driver for thermistor thermometers