Espeasy: Add proper checks and show warnings to users against incorrect configuration

[tedenda]

• [x] Tell user that PulseCounter only works on task 1-4 if configured on task 5-12
• [x] Do not use same name of tasks
• [ ] When changing a name which is used in some rule, add a warning
• [ ] Add a warning when a hostname cannot be resolved
• [ ] Add a warning when a device cannot be detected in a plugin/task (e.g. I2C devices)
• [ ] Add warning/error when delay is set to a too low value in a plugin/task
• [ ] Max length on task namn, value name
• [x] Check that task and value name is different
• [x] Check for non valid chars in names
• [ ] Validate unit number
• [x] Show a warning when performing OTA on a 1MB flash device
• [x] Set msg delay to 100 ms when using a switch
• [x] Check IP settings for all values be filled or none (DHCP)

[TD-er]

Also good to check:

• Do not use same name of tasks.
• When changing a name which is used in some rule, add a warning.
• Add a warning when a hostname cannot be resolved.
• Add a warning when a device cannot be detected in a plugin/task (e.g. I2C devices)
• Add warning/error when delay is set to a too low value in a plugin/task.

[Grovkillen]

Length of task name, value name should also be included in the scope. Also it's not recommended to have the same name for task and value. Spaces is names are also a no-go.

[s0170071]

@tedenda: When adding a task is not working- what does the FreeMem line on the main webpage read ?
e.g.

Free Mem: | 18544 (13888 - duringDataTX)

[TD-er]

Do not allow characters other than numbers for the unit number.
See forum

[TD-er]

Show a warning when performing OTA on a 1MB flash device.
Suggested here.

[TD-er]

Set msg delay to 100 ms when using a switch.
See forum