0a85445 [Core] Add -debugexclude option (random-zebra)

Pull request description:

  Implemented on top of:
  - [x] #1449
  - [x] #1437

  Backports bitcoin#10123

  > setting `-debug` can lead to very noisy debug.logs with subcomponents filling up the log file. See for example https://travis-ci.org/bitcoin/bitcoin/jobs/216767286 where there are hundreds of libevent debug logs.

  This commit adds an option to exclude certain components from debug logging. The usage is:
  ```
  pivxd -debug -debugexclude=<component1> -debugexclude=<component2> ...
  ```

  This finally reduces spammy logs in the functional tests debug, due to libevent and leveldb (bitcoin#10124 was already included backporting the test suite).

ACKs for top commit:
  furszy:
    Code looking good, utACK 0a85445 .
  Fuzzbawls:
    ACK 0a85445

Tree-SHA512: 6ccbe275ab11f3e1739ed117e49db0a2e56db345287cddc7cc18fc1131d7800d0f08a7e93005f70cf45ed8e340580f91c3017532bd2ea28fedb5735409ae068b

d16b7b2 Buffer log messages and explicitly open logs (random-zebra)

Pull request description:

  implemented on top of
  - [x] #1449
  - [x] #1437
  - [x] #1439

  Backports bitcoin#6149

  > Prevents stomping on debug logs in datadirs that are locked by other
  instances and lost parameter interaction messages that can get wiped by
  ShrinkDebugFile().
  The log is now opened explicitly and all emitted messages are buffered
  until this open occurs.  The version message and log cut have also been
  moved to the earliest possible sensible location.

ACKs for top commit:
  furszy:
    utACK d16b7b2
  Fuzzbawls:
    ACK d16b7b2

Tree-SHA512: f3f859181499661641df1ccf118fdb583517c3f4104313df4c200471436e2c456bd9d15164215cfde274b235afdd2afe19a186c214d3c06461f0e3a03bd944b8

f66e50e [Doc] Add logging RPC to release notes (random-zebra)
bf55911 allow libevent logging to be updated during runtime (random-zebra)
ec43b51 Set BCLog::LIBEVENT correctly for old libevent versions. (random-zebra)
cbaf724 [rpc] Add logging rpc (random-zebra)

Pull request description:

  Implemented on top of:
  - [x] #1449
  - [x] #1437
  - [x] #1439
  - [x] #1450

  Backports bitcoin#10150

  > Adds an RPC to get/set active logging categories.
  First commit allows all categories except libevent to be reconfigured during runtime.
  Second commit modifies InitHTTPServer() to allow leveldb logging to be reconfigured during runtime.

ACKs for top commit:
  furszy:
    Really nice 👍 , ACK f66e50e .
  Fuzzbawls:
    ACK f66e50e

Tree-SHA512: 7b735628d341fb8661eb76f57dadc78e69ea63c62edb778450b3d9e3b7137ce06e08ceab835967b923401a9687e5b2605722a9f256e6ed85fc372a0e46086b8f

882ef90 [Doc] Update release notes for `-debuglogfile` (random-zebra)
3d5ad7f test: Add tests for `-debuglogfile` with subdirs (random-zebra)
2c2e36d test: Add test for `-debuglogfile` (random-zebra)
b44a324 Add `-debuglogfile` option (random-zebra)

Pull request description:

  Implemented on top of
  - [x] #1449
  - [x] #1437
  - [x] #1439
  - [x] #1450
  - [x] #1451

  Only last 4 commits are relevant to this PR.
  Backports bitcoin#11781

  > This patch adds an option to configure the name and/or directory of the debug log file.</br></br>
  The user can specify either a relative path, in which case the path is relative to the (network specific) data directory. They can also specify an absolute path to put the log anywhere else in the file system.

  Functional test included.

ACKs for top commit:
  Fuzzbawls:
    ACK 882ef90
  furszy:
    utACK 882ef90

Tree-SHA512: 02a0e6487683e5111765af7296ef7ce035372febf037268d99d29b4c4a2f74bcc40f46a0f5b1bacddc2249c2a7e40255555e83ca9d51bf71d9e054c6e85765cc

5c8e968 [Trivial] Document logtimemicros flag in the help (random-zebra)
4daa10a util: Store debug log file path in BCLog::Logger member. (random-zebra)
2f03e85 scripted-diff: Rename BCLog::Logger member variables. (random-zebra)
303700e util: Refactor GetLogCategory. (random-zebra)
0ae18c0 util: Encapsulate logCategories within BCLog::Logger. (random-zebra)
a2fb3fd util: Move debug file management functions into Logger. (random-zebra)
5a42d82 util: Establish global logger object. (random-zebra)
15c0da4 [Refactor] Complete boost::filesystem namespace in util (random-zebra)
81ddbf4 MOVEONLY: Move logging code from util.{h,cpp} to new files. (random-zebra)

Pull request description:

  Implemented on top of:
  - [x] #1449
  - [x] #1437
  - [x] #1439
  - [x] #1450
  - [x] #1451
  - [x] #1455

  This creates a new class BCLog::Logger to encapsulate all global logging configuration and state.

  Adapted from
  - bitcoin#13021
  - bitcoin#12954

ACKs for top commit:
  Fuzzbawls:
    ACK 5c8e968
  furszy:
    utACK 5c8e968

Tree-SHA512: 0b10a031dd7e32b48485236fbdd8249d011049e6f99e1df145b7dea4cab9e6e67e19d1bb13ff48e99eb2487a8399bbb8298fe851ad8873416fc1053aee0379bc