New Feature: Setting for default prebuild-/postbuild-path

[4ch1m]

Another small feature/improvement. ;-)

I pretty much always want to run the same "prebuild.sh" before building/running any ASM-file (simply to execute 'killall x64', etc.).
ATM I have to place a copy of my "prebuild.sh"-file into the folder where the ASM-file resides.
And if I ever change/update my "prebuild.sh"-file I will have to change/udpate all existing copies of it. :(
(I know that I could use symlinks... but the symlinks also will have to be created manually every time; for every directory I intend to build/run a ASM-file. And Windows-users also might not have the possibility of using symlinks.)

With this PR you can define a default-path where the "prebuild.sh"-file is located via a simple settings-entry.
Any "prebuild.sh" located in the ASM-file-directory will still take precedence; but if none is present we also check the default path.

Oh... and all of this also applies for the "postbuild.sh". :)

[Swoffa]

@4ch1m
Recently i moved all settings to file KickAssembler (C64).sublime-settings, but i found out it was not a good idea, so i moved them back to Preferences.sublime-settings. This makes merge problems for this PR, sorry. Can you fix the conflict by moving your settings to Preferences.sublime-settings?

[og2t]

This will be fantastic to merge. I am using a similar setup where I have .sh script files to build, kill x64 and run the code. I was actually hacking SublimeKickAssemblerC64 build process to trigger my scripts instead altogether until now ;-)

[4ch1m]

@Swoffa: OK.
I just synced with master and adjusted everything accordingly.

[Swoffa]

@4ch1m
Great feature, thanks!

[Swoffa]

@4ch1m
I fixed an issue that environment variables were not added for global pre/post scripts. In master.