[Qt] add all used colors in txtablemodel to guiconstants

- add colors used in TX status decoration
[Qt] simplify return code and return values in txtablemodel

- also move an added space in a string where it belongs
typo fix of booleamn to boolean
prefer const string& over char* in CDB and CWalletDB constructor

- also make parameter of CDBEnv::CheckpointLSN a constant reference
cleanup class private and public areas in walletdb

- only code movement
Merge pull request #4931

93f84d0 cleanup class private and public areas in walletdb (Philip Kaufmann)
22d7e70 prefer const string& over char* in CDB and CWalletDB constructor (Philip Kaufmann)
Merge pull request #4936

c15e483 typo fix of booleamn to boolean (imharrywu)
Remove mention of MacPorts from OSX build docs
Merge pull request #4939

d547ebf Remove mention of MacPorts from OSX build docs (Wladimir J. van der Laan)
Merge pull request #4667

bbad683 [Qt] simplify return code and return values in txtablemodel (Philip Kaufmann)
21f1516 [Qt] add all used colors in txtablemodel to guiconstants (Philip Kaufmann)