[Citadel Development] some work on calendar

some work on calendar https://code.citadel.org?p=citadel.git;a=commitdiff;h=e8e6d8ec8decd3c161a1a78273b1538fe8bdb88b

[Citadel Development] Calendar view: initial call of REPORT method.

Calendar view: initial call of REPORT method. https://code.citadel.org?p=citadel.git;a=commitdiff;h=fd9570c14521f696cccaaf8b8e7e0fa75cfddc2a

[Citadel Development] more noodling on backend detection

more noodling on backend detection https://code.citadel.org?p=citadel.git;a=commitdiff;h=74104e1f70c837bfeec6e957ce7f84a4f969a0ed

[Citadel Development] Test for existing BDB files (not used yet)

Test for existing BDB files (not used yet) https://code.citadel.org?p=citadel.git;a=commitdiff;h=892419cf4747c1c0abea8d1e9bed8ca692aed8eb