Improve/17.4: Create inflowType, inflowPath spec with options LES, TS replacing LESpath spec.

[ombahiwal]

From issue #17

• partly resolving point number 4
• Replace the specification of LESpath and add a way to specify what type of inflow will be executed (see here).
• inflowType and InflowPath specification added by replacing LESpath spec in FFCaseCreation class.
• Currently the inflowType takes two options LES and TS (with TS as default i.e. TurboSim driven)
• inflowPath can be set to None if inflowType is TS
• Additional configuration logic can be added where indicated for LES or Mann inflows.

[rthedin]

Thank you @ombahiwal for your contribution!