Updated usage print.
Included new insatllation method
Update LICENSE.txt
Fixed even more filename encoding issues

Filenames are correctly decoded but sometimes they are (were?) not
encoded back in debug prints. Sometimes thoug they do not require taking
this step so it's usually guess and try method to figure out which can
break SubConvert.
Merge branch 'gui' into dev
Issue #36: ddd -g option to SubConvert console
Modified MPL2 test subtitle

Reason: issue #42
Fix issue #42: MPL2 one-digit-time error

Also, when converting to MPL2, Subconvert no longer prepends unnecessary
zeroes to subtitle times.
Fixed issue #44: Keeping logs

Unnecessary, file-specific GUI logs are no longer kept when Subconvert
is startingarted via "subconvert -g" or without "--keep-logs" flag. This
provides similar and expected user experience for the two ways of
starting a GUI.
Removed unnecessary print
Regenerated messages.pot
Updated Polish translation
Modified Changelog for Release 0.9
Merge branch 'dev'
Added #38: installer dependency check
Issue #45: created full UT regression for FrameTime

Status of issue: unfinished
Fixed issues with inacurrate FrameTime

Fix involves some hacks for inaccurate float arithmetic
Removed unnecessary imports
Added random check and some logs to FrameTime UT.
Added Subconvert logo icons